Keratosis Pilaris, Lichen Planus, Pityriasis Rosea, Psoriasis

Keratosis Pilaris

Keratosis pilaris is a common disorder in which dead cells shed from the upper layer of skin plug the openings of hair follicles.

The cause is not known, although heredity probably plays a role. Also, people with atopic dermatitis are more likely to have keratosis pilaris.

The plugs or bumps that occur in keratosis pilaris make the skin feel rough (like chicken skin) and dry. Sometimes the plugs resemble small pimples. Generally, these plugs do not itch or hurt and cause only cosmetic problems. The upper arms, thighs, and buttocks are most commonly affected. The face may break out as well, particularly in children. Plugs are more likely to develop in cold weather and to clear up in the summer.

Treatment is not needed unless the person is bothered by the appearance of the disorder. Skin moisturizers are the main treatment. Creams with salicylic acid, lactic acid, or tretinoin can also be used. Keratosis pilaris is likely to come back when treatment is stopped.


Lichen Planus
Lichen planus, a recurring itchy disease, starts as a rash of small, discrete red or purple bumps that then combine and become rough, scaly patches.

The cause of lichen planus is not known, but it may be a reaction by the immune system to a variety of drugs (especially gold, bismuth, arsenic, quinine, quinidine, and quinacrine), chemicals (especially certain chemicals used to develop color photographs), and infectious organisms. The disorder itself is not infectious.

Symptoms

The rash of lichen planus almost always itches, sometimes severely. The bumps are usually violet and have angular borders; when light is directed at them from the side, the bumps display a distinctive sheen. New bumps may form wherever scratching or a mild skin injury occurs. Sometimes a dark discoloration remains after the rash heals.

Usually, the rash is evenly distributed on both sides of the body—most commonly on the torso, on the inner surfaces of the wrists, on the legs, on the head of the penis, and in the vagina. About half of those who get lichen planus also develop mouth sores. The face is less often affected. On the legs, the rash may become especially large, thick, and scaly. The rash sometimes results in patchy baldness on the scalp.

Lichen planus in the mouth usually results in a bluish white patch that forms in lines. This type of mouth patch often does not hurt, and the person may not know it is there. Sometimes painful sores form in the mouth, which often interfere with eating and drinking.

Prognosis and Treatment

Lichen planus usually clears up by itself after 1 or 2 years, although it sometimes lasts longer, especially when the mouth is involved. Symptoms recur in about 20% of people. Prolonged treatment may be needed during outbreaks of the rash; between outbreaks, no treatment is needed. People with mouth sores have a slightly increased risk of oral cancer, but the rash on the skin does not turn cancerous.

Drugs or chemicals that may be causing lichen planus should be avoided, and standard treatments can be used to relieve itching. Corticosteroids may be injected into the bumps, applied to the skin, or taken by mouth, sometimes with other drugs, such as acitretin or cyclosporin. Phototherapy (exposure to ultraviolet light) combined with the use of psoralens (drugs that make the skin more sensitive to the effects of ultraviolet light) may also be helpful. This treatment is called PUVA (psoralens plus ultraviolet A). For painful mouth sores, a mouthwash containing lidocaine, an anesthetic, may be used before meals to form a pain-killing coating.



Pityriasis Rosea
Pityriasis rosea is a mild disease that causes many small patches of scaly, rose-colored, inflamed skin.

The cause of pityriasis rosea is not certain but may be an infectious agent; however, the disorder is not thought to be contagious. It can develop at any age but is most common in young adults. It usually appears during spring and autumn.

Symptoms

Pityriasis rosea causes a rose-red or light-tan patch of skin about 1 to 4 inches in diameter that doctors call a herald or mother patch. This round or oval area usually develops on the torso. Sometimes the patch appears without any previous symptoms, but some people have a vague feeling of illness, loss of appetite, fever, and joint pain a few days before. In 5 to 10 days, many similar but smaller patches appear on other parts of the body. These secondary patches are most common on the torso, especially along and radiating from the spine. Most people with pityriasis rosea have some itching, and in some people the itching can be severe.

Diagnosis and Treatment

A doctor usually makes the diagnosis based on the appearance of the rash, particularly the herald patch. Usually the rash goes away in 4 to 5 weeks without treatment, although sometimes it lasts for 2 months or more. Both artificial and natural sunlight may speed clearing and relieve the itching. Other standard treatments for itching may be used as needed. Corticosteroids taken by mouth are necessary only for very severe itching.


Psoriasis

Psoriasis is a chronic, recurring disease that causes one or more raised, red patches that have silvery scales and a distinct border between the patch and normal skin.

The patches of psoriasis occur because of an abnormally high rate of growth of skin cells. The reason for the rapid cell growth is unknown, but a problem with the immune system is thought to play a role. The disorder often runs in families. Psoriasis is common, affecting 2 to 4% of whites; blacks are less likely to get the disease.

Symptoms

Psoriasis begins most often in people aged 10 to 40, although people in all age groups are susceptible.

It usually starts as one or more small patches on the scalp, elbows, knees, back, or buttocks. The first patches may clear up after a few months or remain, sometimes growing together to form larger patches. Some people never have more than one or two small patches, and others have patches covering large areas of the body. Thick patches or patches on the palms of the hands, soles of the feet, or skinfolds of the genitals are more likely to itch or hurt, but many times the person has no symptoms. Although the patches do not cause extreme physical discomfort, they are very obvious and often embarrassing to the person. The psychologic distress caused by psoriasis can be severe. Many people with psoriasis also have deformed, thickened, pitted nails.

Psoriasis persists throughout life but may come and go. Symptoms are often diminished during the summer when the skin is exposed to bright sunlight. Some people may go for years between occurrences. Psoriasis may flare up for no apparent reason or as a result of a variety of circumstances. Flare-ups often result from conditions that irritate the skin, such as minor injuries and severe sunburn. Sometimes flare-ups follow infections, such as colds and strep throat. Flare-ups are more common in the winter and after stressful situations. Many drugs, such as antimalarial drugs, lithium, and beta-blockers, can also cause psoriasis to flare up.

Some uncommon types of psoriasis can have more serious effects. Psoriatic arthritis produces joint pain and swelling (see Rheumatoid Arthritis and Other Types of Inflammatory Arthritis: Psoriatic Arthritis). Erythrodermic psoriasis causes all of the skin on the body to become red and scaly. This form of psoriasis is serious because, like a burn, it keeps the skin from serving as a protective barrier against injury and infection. In another uncommon form of psoriasis, pustular psoriasis, large and small pus-filled blisters (pustules) form on the palms of the hands and soles of the feet. Sometimes, these pustules are scattered on the body.

Treatment

Many drugs are available to treat psoriasis. Most often, a combination of drugs is used, depending on the severity and extent of the person's symptoms.

Topical drugs (drugs applied to the skin) are used most commonly. Nearly everyone with psoriasis benefits from skin moisturizers (emollients). Other topical agents include corticosteroids, often used together with calcipotriene, a vitamin D derivative, or coal or pine tar. Tazarotene or anthralin may also be used. Very thick patches can be thinned with ointments containing salicylic acid, which make the other drugs more effective. Many of these drugs are irritating to the skin, and doctors must find which ones work best for each person.

Phototherapy (exposure to ultraviolet light) also can help clear up psoriasis for several months at a time. Phototherapy is often used in combination with various topical drugs, particularly when large areas of skin are involved. Traditionally, treatment has been with phototherapy combined with the use of psoralens (drugs that make the skin more sensitive to the effects of ultraviolet light). This treatment is called PUVA (psoralens plus ultraviolet A). Some doctors are now using narrow-band ultraviolet B (UVB) treatments, which are equally effective but avoid the need to use psoralens and the side effects they cause, such as extreme sensitivity to sunshine.

For serious forms of psoriasis and psoriatic arthritis, drugs taken by mouth are used. These drugs include cyclosporine, methotrexate, and acitretin. Cyclosporine is an immunosuppressant drug. Cyclosporine may cause high blood pressure and damage the kidneys. Methotrexate interferes with the growth and multiplication of skin cells. Doctors use methotrexate for people whose psoriasis does not respond to other forms of therapy. Liver damage and impaired immunity are possible side effects. Acitretin is similar to the acne drug isotretinoin and is particularly effective in pustular psoriasis but often raises fat (lipid) levels in the blood and might cause problems with the liver and bones. It can also cause birth defects and should not be taken by a woman who might get pregnant.


Adapted from: Merck & Co., Inc.

Granuloma Annulare, Itching

Granuloma Annulare

Granuloma annulare is a chronic, harmless skin disorder of unknown cause in which small, firm, raised bumps form a ring with normal or slightly sunken skin in the center.

The bumps are red, violet, or flesh-colored; a person may have one ring or several. The bumps usually cause no pain or itching; they most often form on the feet, legs, hands, or fingers of children and adults. In a few people, clusters of granuloma annulare bumps erupt when the skin is exposed to the sun.

Most often, granuloma annulare heals without any treatment. Corticosteroid creams under waterproof bandages, surgical tape saturated with a corticosteroid, or injected corticosteroids may help clear up the rash. People with large affected areas often benefit from treatment that combines phototherapy (exposure to ultraviolet light) with the use of psoralens (drugs that make the skin more sensitive to the effects of ultraviolet light). This treatment is called PUVA (psoralens plus ultraviolet A).

Itching

Itching (pruritus) is a sensation that instinctively demands scratching.

Itching may be caused by a skin disorder or by a disease that affects the whole body (systemic disease). Skin disorders that cause severe itching include infestations with parasites (scabies, mites, or lice), insect bites, hives, atopic dermatitis, and allergic and contact dermatitis. These disorders usually also produce a rash. Systemic diseases that can cause itching include liver disease, kidney failure, lymphomas, leukemias and other blood disorders, and, occasionally, thyroid disease, diabetes, and cancer. However, itching from these diseases usually does not result in a rash.

Many drugs can cause itching, including barbiturates and aspirin as well as any drug to which a person has an allergy.

Itching is also common during the later months of pregnancy. Usually, pregnancy-related itching does not indicate any abnormality, but it can result from mild liver problems.

Often, contact with wool clothing or irritants, such as solvents or cosmetics, causes itching. Dry skin (xerosis), which is especially common in older people, can cause severe, widespread itching. Dry skin also can result from cold weather or prolonged exposure to water. Hot baths typically worsen itching.

The act of scratching can itself irritate the skin and lead to more itching, creating an itching-scratching-itching cycle. Vigorous scratching may cause redness and deep scrapes in the skin. In some people, even gentle scratching causes raised, red streaks that can itch intensely. Prolonged scratching and rubbing can thicken and scar the skin

When the Skin Is Dry
Normal skin owes its soft, pliable texture to its water content. To help protect against water loss, the outer layer of skin contains oil, which slows evaporation and holds moisture in the deeper layers of skin. If the oil is depleted, the skin becomes dry.

Dry skin (xerosis) is common, especially in people past middle age. Common causes are cold weather and frequent bathing. Bathing washes away surface oils, allowing the skin to dry out. Dry skin may become irritated and often itches—sometimes it sloughs off in small flakes and scales. Scaling most often affects the lower legs. Rubbing or scratching dry skin can lead to infection and scarring.

A form of severe dry skin is called ichthyosis. Ichthyosis can be an inherited disorder or can result from a number of other medical problems, such as an underactive thyroid gland, lymphoma, AIDS, and sarcoidosis.

The key to treating simple dry skin is keeping the skin moist. Taking fewer baths allows protective oils to remain on the skin. Moisturizing ointments or creams containing petroleum jelly, mineral oil, or glycerin also can hold water in the skin. Harsh soaps, detergents, and the perfumes in some moisturizers irritate the skin and may further dry it.

When scaling is a problem, solutions or creams containing salicylic or lactic acid or urea may help remove the scales. For some forms of severe ichthyosis, creams containing substances related to vitamin A, such as tretinoin, help the skin shed excessive scales.

Diagnosis

Doctors try to determine the cause of itching to eliminate it. Often, the cause is obvious, such as an insect bite or poison ivy. Itching that lasts longer than a few days or that comes and goes frequently without an obvious cause usually requires testing. If an allergy is suspected, skin tests may be performed. If a systemic disease is suspected, blood tests are usually performed to check liver function, kidney function, and blood sugar levels. The number of eosinophils, a type of white blood cell, may be checked as well, because a high number may indicate an allergic reaction. Sometimes, the doctor may have a person discontinue one or more drugs to see if the itching is relieved. A biopsy or skin scraping may help identify the cause, including an infectious one.

Treatment

For itching of any cause, bathing should be kept brief and preferably in cool or lukewarm water with very little or no soap. The skin should be patted dry gently rather than rubbed vigorously. Many people with itching benefit from an over-the-counter moisturizing cream applied right after bathing. The moisturizer should be odorless and colorless, because additives that provide color or scent may irritate the skin and even cause itching. Fingernails, especially children's, should be kept short to minimize abrasions from scratching. Coating the affected area with soothing compounds, such as menthol, camphor, chamomile, eucalyptus, or calamine, also can help.

Taking antihistamines by mouth may decrease itching. Some antihistamines, such as hydroxyzine and diphenhydramine, usually cause sleepiness and dry mouth and are mainly used at bedtime. Other antihistamines, such as loratadine and cetirizine, usually do not cause sleepiness. Generally, creams containing antihistamines (such as diphenhydramine) should not be used, because they can themselves cause an allergic reaction.

Corticosteroid creams decrease inflammation and control itching and may be used when itching is limited to a small area. Itching from some conditions, such as poison ivy, may require high-strength corticosteroid creams. However, only mild corticosteroids, such as 1% hydrocortisone, should be applied to the face and genitals, because stronger corticosteroids may thin the sensitive skin in these areas. Also, powerful corticosteroid creams applied over large areas or for a long time can cause serious medical problems, especially in infants, because these drugs are absorbed into the bloodstream. Oral corticosteroids are sometimes used when large areas of the body are involved.

Specific treatments may be needed. For example, when fungal, parasitic, or bacterial infections cause itching, topical or systemic drugs may be required. Topical drugs are applied directly to the affected area of the skin. Systemic drugs are taken by mouth or injected and are distributed throughout the body.

Adapted from: Merck & Co., Inc.

Drug Rashes, Erythema Multiforme, Erythema Nodosum

Drug Rashes
Drug rashes are a side effect of a drug that manifests as a skin reaction.

Most drug rashes result from an allergic reaction to the drug. The drug does not have to be applied to the skin to cause a drug rash. Sometimes a person can be sensitized to a drug by one exposure, and other times sensitization occurs only after many exposures to a substance. Later exposure to the drug may trigger an allergic reaction, such as a rash.

Sometimes a rash develops directly without involving an allergic reaction. For example, corticosteroids and lithium produce a rash that looks like acne, and anticoagulants (blood thinners) may cause bruising when blood leaks under the skin. Other important nonallergic rashes that may result from drugs are those that occur in Stevens-Johnson syndrome, toxic epidermal necrolysis, and erythema nodosum.

Certain drugs make the skin particularly sensitive to the effects of sunlight (photosensitivity). These drugs include certain antipsychotics, tetracycline, sulfa antibiotics, chlorothiazide, and some artificial sweeteners. No rash appears when the drug is taken, but later exposure to the sun produces a reddened area of skin that is sometimes itchy or that appears grayish blue.

Symptoms

Drug rashes vary in severity from mild redness with tiny bumps over a small area to peeling of the entire skin. Rashes may appear suddenly within minutes after a person takes a drug, or they may be delayed for hours or days. People with an allergic rash often have other allergic symptoms—runny nose, watery eyes, wheezing, and even collapse from dangerously low blood pressure. Hives are very itchy, whereas other drug rashes itch little, if at all.

Diagnosis and Treatment

Figuring out whether a drug is responsible may be difficult because a rash can result from only a minute amount of a drug, it can erupt long after a person has taken a drug, and it can persist for weeks or months after a person has discontinued a drug. Every drug a person has taken is suspect, including those bought without a prescription; even eye drops, nose drops, and suppositories are possible causes. Sometimes the only way to determine which drug is causing a rash is to have the person discontinue all but life-sustaining drugs. Whenever possible, chemically unrelated drugs are substituted. If there are no such substitutes, the person starts taking the drugs again one at a time to see which one causes the reaction. However, this method can be hazardous if the person had a severe allergic reaction to the drug. Skin testing is not helpful, except when penicillin is the suspect drug.

Most drug reactions disappear when the responsible drug is discontinued. Standard itching treatments are used as needed. Serious allergic eruptions, particularly those accompanied by significant symptoms such as wheezing or difficulty breathing, are treated with injections of epinephrine, diphenhydramine, and a corticosteroid.


Erythema Multiforme
Erythema multiforme is a recurring disorder characterized by patches of red, raised skin that often look like targets and usually are distributed symmetrically over the body.

Most cases are caused by a reaction to infection with the herpes simplex virus (see Viral Infections: Herpes Simplex Virus (HSV) Infections). This viral infection is apparent as visible cold sores in about two thirds of people before the erythema multiforme appears. Doctors are not sure if other infectious diseases also cause erythema multiforme. Doctors are unsure exactly how herpes simplex causes this disorder, but a type of immune reaction is suspected.

Symptoms

Usually, erythema multiforme appears suddenly, with reddened patches erupting on the arms, legs, and face. Sometimes the rash is also present on the palms or soles. The red patches are distributed equally on both sides of the body; these red areas often develop red concentric rings with purple-gray centers (target or iris lesions) and small blisters. The reddened areas usually are symptomless, although they sometimes itch mildly. Painful blisters often form on the lips and lining of the mouth but do not involve the eyes.

Attacks of erythema multiforme may last 2 to 4 weeks. Some people have only one attack, but some have recurrences an average of 6 times a year for almost 10 years. Recurrences are more common in the spring and can probably be triggered by sunlight. The frequency of recurrence usually decreases with time.

Treatment

Erythema multiforme may resolve on its own. If itching is bothersome, standard treatments may be used. Corticosteroids given by mouth may be helpful. If painful mouth blisters make eating difficult, a topical anesthetic, such as lidocaine, may be applied. If oral intake is still poor, nutrition and fluids are given intravenously. People with frequent recurrences may benefit from an antiviral drug, such as acyclovir, given at the first sign of an outbreak.


Erythema Nodosum
Erythema nodosum is an inflammatory disorder that produces tender red bumps (nodules) under the skin, most often over the shins but occasionally on the arms and other areas.

Quite often, erythema nodosum is a symptom of some other disease or of sensitivity to a drug. Young adults, particularly women, are most prone to the disorder, which may recur for months or years. Bacterial, fungal, or viral infections may also cause erythema nodosum.

Streptococcal infection is one of the most common causes of erythema nodosum, particularly in children. Sarcoidosis, ulcerative colitis, and various drugs, such as sulfa antibiotics and oral contraceptives, are other common causes. Numerous other infections and several types of cancer are also thought to cause the eruption.

Erythema nodosum nodules usually appear on the shins and resemble raised bumps and bruises that gradually change from pink to bluish brown. Fever and joint pain are common; lymph nodes in the chest occasionally become enlarged and are detected with a chest x-ray. The painful nodules are usually the telltale sign for the doctor. Evaluation includes chest x-ray, blood tests, and skin biopsy.

Treatment

Drugs that might be causing erythema nodosum are discontinued, and any underlying infections are treated. If the disorder is caused by a streptococcal infection, a person may have to take antibiotics, such as penicillin, or a cephalosporin.

The nodules may go away in 3 to 6 weeks without treatment. Bed rest and nonsteroidal anti-inflammatory drugs (NSAIDs) may help relieve the pain caused by the nodules. Individual nodules may also be treated by injecting them with a corticosteroid; when a person has many nodules, corticosteroid or potassium iodide tablets sometimes are prescribed to speed relief of pain.


Adapted from: Merck & Co., Inc

Skin Itching and Noninfectious Rashes

Introduction
Itching and rashes may develop as the result of infection or irritation or from a reaction of the immune system. Some rashes occur mostly in children, whereas others almost always occur in adults. Sometimes an immune reaction is triggered by substances a person touches or eats, but many times doctors do not know why the immune system reacts to produce a skin rash.

The diagnosis of most noninfectious skin rashes is based on the appearance of the rash. The cause of a rash cannot be determined by blood tests, and tests of any kind are rarely performed. However, persistent rashes, particularly those that do not respond to treatment, may lead the doctor to perform a skin biopsy, in which a small piece of skin is surgically removed for examination under a microscope. Also, if the doctor suspects a contact allergy as the cause, skin tests may be performed.


Dermatitis
Dermatitis (eczema) is inflammation of the upper layers of the skin, causing itching, blisters, redness, swelling, and often oozing, scabbing, and scaling.

Dermatitis is a broad term covering many different disorders that all result in a red, itchy rash. The term eczema is sometimes used for dermatitis. Some types of dermatitis affect only specific parts of the body, whereas others can occur anywhere. Some types of dermatitis have a known cause; others do not. However, dermatitis is always the skin's way of reacting to severe dryness, scratching, a substance that is causing irritation, or an allergen. Typically, that substance comes in direct contact with the skin, but sometimes the substance is swallowed. In all cases, continuous scratching and rubbing may eventually lead to thickening and hardening of the skin.

Dermatitis may be a brief reaction to a substance. In such cases it may produce symptoms, such as itching and redness, for just a few hours or a day or two. Chronic dermatitis persists over a period of time. The hands and feet are particularly vulnerable to chronic dermatitis, because the hands are in frequent contact with many foreign substances and the feet are in the warm, moist conditions created by socks and shoes that favor fungal growth.

Chronic dermatitis may represent a contact, fungal, or other dermatitis that has been inadequately diagnosed or treated, or it may be one of several chronic skin disorders of unknown origin, such as pompholyx (see Itching and Noninfectious Rashes: Pompholyx) or hyperkeratotic palmar eczema. Because chronic dermatitis produces cracks and blisters in the skin, any type of chronic dermatitis may lead to bacterial infection.

Contact Dermatitis
Contact dermatitis is skin inflammation caused by direct contact with a particular substance; the rash is very itchy, is confined to a specific area, and often has clearly defined boundaries.

Substances can cause skin inflammation by one of two mechanisms—irritation (irritant contact dermatitis) or allergic reaction (allergic contact dermatitis).

Irritant contact dermatitis occurs when a chemical substance causes direct damage to the skin. Typical irritating substances are acids, alkalis (such as drain cleaners), solvents (such as acetone in nail polish remover), and strong soaps. Some of these chemicals cause skin changes within a few minutes, whereas others require longer exposure. People vary in the sensitivity of their skin to irritants. Even very mild soaps and detergents may irritate the skin of some people after frequent or prolonged contact.

Allergic contact dermatitis is a reaction by the body's immune system to a substance contacting the skin. Sometimes a person can be sensitized by only one exposure, and other times sensitization occurs only after many exposures to a substance. After a person is sensitized, the next exposure causes itching and dermatitis within 4 to 24 hours, although some people, particularly older people, do not develop a reaction for 3 to 4 days.

Thousands of substances can result in allergic contact dermatitis. The most common include substances found in plants such as poison ivy, rubber (latex), antibiotics, fragrances, preservatives, and some metals (nickel, cobalt). About 10% of women are allergic to nickel, a common component of jewelry. People may use (or be exposed to) substances for years without a problem, then suddenly develop an allergic reaction. Even ointments, creams, and lotions used to treat dermatitis can cause such a reaction. People may also develop dermatitis from many of the materials they touch while at work (occupational dermatitis).

Sometimes contact dermatitis results only after a person touches certain substances and then exposes the skin to sunlight (photoallergic or phototoxic contact dermatitis). Such substances include sunscreens, aftershave lotions, certain perfumes, antibiotics, coal tar, and oils.

Common Causes of Allergic Contact Dermatitis

Cosmetics: Hair-removing chemicals, nail polish, nail polish remover, deodorants, moisturizers, aftershave lotions, perfumes, sunscreens

Metal compound (in jewelry): Nickel

Plants: Poison ivy, poison oak, poison sumac, ragweed, primrose, thistle

Drugs in skin creams: Antibiotics (sulfonamides, neomycin), antihistamines (diphenhydramine, promethazine), anesthetics (benzocaine), antiseptics (thimerosal), stabilizers

Chemicals used in clothing manufacturing: Tanning agents in shoes; rubber accelerators and antioxidants in gloves, shoes, undergarments, other apparel


Symptoms and Diagnosis

Regardless of cause or type, contact dermatitis results in itching and a rash. The itching is usually severe, but the rash varies from a mild, short-lived redness to severe swelling and large blisters. Most commonly, the rash contains tiny blisters. The rash develops only in areas contacted by the substance. However, the rash appears earlier in thin, sensitive areas of skin, and later in areas of thicker skin or on skin that had less contact with the substance, giving the impression that the rash has spread. Touching the rash or blister fluid cannot spread contact dermatitis to other people or to other parts of the body that did not make contact with the substance.

Determining the cause of contact dermatitis is not always easy. Most people are unaware of all the substances that touch their skin. Often, the location of the initial rash is an important clue, particularly if it occurs under an item of clothing or jewelry or only in areas exposed to sunlight. However, many substances that people touch with their hands are unknowingly transferred to the face, where the more sensitive facial skin may react even if the hands do not.

If a doctor suspects contact dermatitis and a process of elimination does not pinpoint the cause, patch testing can be performed. For this test, small patches containing substances that commonly cause dermatitis are placed on the skin for 1 to 2 days to see if a rash develops beneath one of them. Although useful, patch testing is complicated. People may be sensitive to many substances, and the substance they react to on a patch may not be the cause of their dermatitis. A doctor must decide which substances to test based on what a person might have been exposed to.

Prevention and Treatment

Contact dermatitis can be prevented by avoiding contact with the causative substance. If contact does occur, the material should be washed off immediately with soap and water. If circumstances risk ongoing exposure, gloves and protective clothing may be helpful. Barrier creams are also available that can block certain substances, such as poison ivy and epoxy resins, from contacting the skin. Desensitization with injections or tablets of the causative substance is not effective in preventing contact dermatitis.

Treatment is not effective until there is no further contact with the substance causing the problem. Once the substance is removed, the redness usually disappears after a week. Blisters may continue to ooze and form crusts, but they soon dry. Residual scaling, itching, and temporary thickening of the skin may last for days or weeks.

Itching can be relieved with a number of topical or oral drugs. In addition, small areas of dermatitis can be soothed by applying pieces of gauze or thin cloth dipped in cool water or aluminum acetate (Burow's solution) several times a day for an hour. Larger areas may be treated with short, cool tub baths with or without colloidal oatmeal. The doctor may drain fluid from large blisters, but the blister is not removed.


Poison Ivy Dermatitis
About 50 to 70% of people are sensitive to the plant oil urushiol contained in poison ivy, poison oak, and poison sumac. Similar oils are also present in the shells of cashew nuts; the leaves, sap, and fruit skin of the mango; and Japanese lacquer. Once a person has been sensitized by contact with these oils, subsequent exposure produces a contact dermatitis.

The oils are quickly absorbed into the skin but may remain active on clothing, tools, and pet fur for long periods of time. Smoke from burning plants also contains the oil and may cause a reaction in certain people. Sensitivity to poison ivy tends to run in families.

Symptoms begin from 8 to 48 hours after contact and consist of intense itching, a red rash, and multiple blisters, which may be tiny or very large. Typically, the blisters occur in a straight line following the track where the plant brushed along the skin. The rash may appear at different times in different locations either because of repeat contact with contaminated clothing and other objects or because some parts of the skin are more sensitive than others. The blister fluid itself is not contagious. The itching and rash last for 2 to 3 weeks.

Recognition and avoidance of contact with the plants is the best prevention. A number of commercial barrier creams and lotions can be applied before exposure to minimize, but not completely prevent, absorption of oil by the skin. The oil can soak through latex rubber gloves. Washing of the skin with soap and water prevents absorption of the oil if done immediately. Stronger solvents, such as acetone, alcohol, and various commercial products, are probably no more effective. Desensitization with various shots or pills or by eating poison ivy leaves is not effective.

Treatment helps relieve symptoms but does not shorten the duration of the rash. The most effective treatment is with corticosteroids. Small areas of rash are treated with strong topical corticosteroids, such as triamcinolone, clobetasol, or diflorasone —except on the face and genitals, where only mild corticosteroids, such as 1% hydrocortisone, should be applied. People with large areas of rash or significant facial swelling are given high-dose corticosteroids taken by mouth. Cool compresses wet with water or aluminum acetate may be used on large blistered areas. Antihistamines given by mouth may help with itching. Lotions and creams containing antihistamines are seldom used.


Atopic Dermatitis
Atopic dermatitis is chronic, itchy inflammation of the upper layers of the skin that often develops in people who have hay fever or asthma and in people who have family members with these conditions.

Atopic dermatitis is one of the most common skin diseases, affecting 15 million people in the United States. Almost 66% of people with the disorder develop it before age 1, and 90% by age 5. In half of these people, the disorder will be gone by the teenage years; in others, it is lifelong.

Doctors do not know what causes atopic dermatitis, but people with it usually have many allergic disorders, particularly asthma, hay fever, and food allergies. The relationship between the dermatitis and these disorders is not clear; atopic dermatitis is not an allergy to a particular substance. Atopic dermatitis is not contagious.

Many conditions can make atopic dermatitis worse, including emotional stress, changes in temperature or humidity, bacterial skin infections, and contact with irritating clothing (especially wool). In some infants, food allergies may provoke atopic dermatitis.

Symptoms

Infants may develop red, oozing, crusted rashes on the face, scalp, diaper area, hands, arms, feet, or legs. Large areas of the body may be affected. In older children and adults, the rash often occurs (and recurs) in only one or a few spots, especially on the hands, upper arms, in front of the elbows, or behind the knees.

Although the color, intensity, and location of the rash vary, the rash always itches. The itching often leads to uncontrollable scratching, triggering a cycle of itching-scratching-itching that makes the problem worse. Scratching and rubbing can also tear the skin, leaving an opening for bacteria to enter and cause infections.

In people with atopic dermatitis, infection with the herpes simplex virus, which usually affects a small area with tiny, slightly painful blisters (see Viral Infections: Herpes Simplex Virus (HSV) Infections), may produce a serious illness with widespread dermatitis, blistering, and high fever (eczema herpeticum).

Diagnosis and Treatment

A doctor makes the diagnosis based on the typical pattern of the rash and often on whether other family members have allergies.

No cure exists, but itching can be relieved with topical or oral drugs. Certain other measures can help. Avoiding contact with substances known to irritate the skin or foods that the person is sensitive to can prevent a rash. The skin should be kept moist, either with commercial moisturizers or with petroleum jelly or vegetable oil. Moisturizers are best applied after bathing, while the skin is damp. To limit the use of corticosteroids in people being treated for long periods, doctors sometimes replace the corticosteroids with petroleum jelly for a week or more at a time. Corticosteroid tablets are a last resort for people with stubborn cases.

Phototherapy (exposure to ultraviolet light) often helps adults. This treatment is rarely recommended for children because of its potential long-term side effects, including skin cancer and cataracts.

For severe cases, the immune system can be suppressed with cyclosporine taken by mouth or tacrolimus used as an ointment. Zafirlukast, a new oral drug used to prevent asthma attacks, may also be helpful in treating atopic dermatitis.


Seborrheic Dermatitis
Seborrheic dermatitis is chronic inflammation of unknown cause that causes scales on the scalp and face and occasionally on other areas.

Seborrheic dermatitis occurs most often in infants, usually within the first 3 months of life, and between the ages of 30 and 70. The disorder is more common in men, often runs in families, and is worse in cold weather. A form of seborrheic dermatitis also occurs in as many as 85% of people with AIDS.

Symptoms

Seborrheic dermatitis usually begins gradually, causing dry or greasy scaling of the scalp (dandruff), sometimes with itching but without hair loss. In more severe cases, yellowish to reddish scaly pimples appear along the hairline, behind the ears, in the ear canal, on the eyebrows, on the bridge of the nose, around the nose, on the chest, and on the upper back. In infants younger than 1 month of age, seborrheic dermatitis may produce a thick, yellow, crusted scalp rash (cradle cap) and sometimes yellow scaling behind the ears and red pimples on the face. Frequently, a stubborn diaper rash accompanies the scalp rash. Older children and adults may develop a thick, tenacious, scaly rash with large flakes of skin.

Treatment

The scalp can be treated with a shampoo containing pyrithione zinc, selenium sulfide, an antifungal drug, salicylic acid and sulfur, or tar. The person usually uses the medicated shampoo every other day until the dermatitis is controlled and then twice weekly. Ketoconazole cream is often effective as well. In adults, thick crusts and scales, if present, can be loosened with overnight application of corticosteroids or salicylic acid under a shower cap.

Often, treatment must be continued for many weeks; if the dermatitis returns after the treatment is discontinued, treatment can be restarted. Topical corticosteroids are also used on the head and other affected areas. On the face, only mild corticosteroids, such as 1% hydrocortisone, should be used. Even mild corticosteroids must be used cautiously, because long-term use can thin the skin and cause other problems.

In infants and young children who have a thick scaly rash on the scalp, salicylic acid in mineral oil can be rubbed gently into the rash with a soft toothbrush at bedtime. The scalp can also be shampooed daily with mild baby shampoo, and 1% hydrocortisone cream can be rubbed into the scalp.


Nummular Dermatitis

Nummular dermatitis is a persistent, usually itchy, rash and inflammation characterized by coin-shaped spots with tiny blisters, scabs, and scales.

The cause is unknown. Nummular dermatitis usually affects middle-aged people, occurs along with dry skin, and is most common in winter. However, the rash may come and go without any apparent reason.

The round spots start as itchy patches of pimples and blisters that later ooze and form crusts. The rash may be widespread. Often, spots are more obvious on the backs of the arms or legs and on the buttocks, but they also appear on the torso.

Most people benefit from skin moisturizers. Other treatments include antibiotics taken by mouth, corticosteroid creams and injections, and phototherapy (exposure to ultraviolet light). All treatments, however, are often unsatisfactory.

Generalized Exfoliative Dermatitis

Generalized exfoliative dermatitis (erythroderma) is severe inflammation that causes the entire skin surface to become red, cracked, and covered with scales.

Certain drugs (especially penicillins, sulfonamides, isoniazid, phenytoin, and barbiturates) may cause this disorder. In some cases, it is a complication of other skin diseases, such as atopic dermatitis, psoriasis, and contact dermatitis. Certain lymphomas (cancers of the lymph nodes (see Lymphomas: Introduction) may also cause generalized exfoliative dermatitis. In many cases, the cause is unknown.

Symptoms and Diagnosis

Exfoliative dermatitis may start rapidly or slowly. At first the entire skin surface becomes red and shiny. Then the skin becomes scaly, thickened, and sometimes crusted. Sometimes the hair and nails fall out. Some people have itching and swollen lymph nodes. Although many people have a fever, they may feel cold because so much heat is lost through the damaged skin. Large amounts of fluid and protein may seep out, and the damaged skin is a poor barrier against infection.

Because symptoms of exfoliative dermatitis are similar to those of skin infection, doctors send samples of skin and blood to the laboratory to exclude infection as a cause.

Treatment

Early diagnosis and treatment are important in preventing infection from developing in the affected skin and in keeping fluid and protein loss from becoming life threatening.

People with severe exfoliative dermatitis often need to be hospitalized and given antibiotics (for infection), intravenous fluids (to replace the fluids lost through the skin), and nutritional supplements. Care may include the use of drugs and heated blankets to control body temperature. Cool baths followed by applications of petroleum jelly and gauze may help protect the skin. Corticosteroids (such as prednisone) given by mouth or intravenously are used only when other measures are unsuccessful or the disease worsens. Any drug or chemical that could be causing the dermatitis should be eliminated. If lymphoma is causing the dermatitis, treatment of the lymphoma is helpful.


Stasis Dermatitis
Stasis dermatitis is inflammation on the lower legs from pooling of blood and fluid.

Stasis dermatitis tends to occur in people who have varicose (dilated, twisted) veins (see Venous Disorders: Varicose Veins) and swelling (edema). It usually occurs on the ankles but may spread upward to the knees. At first, the skin becomes reddened and mildly scaly. Over several weeks or months, the skin turns dark brown. Eventually, areas of the skin may break down and form an open sore (ulcer), typically near the ankle. Ulcers sometimes become infected with bacteria. Stasis dermatitis makes the legs feel itchy and swollen, but not painful. Ulcers are usually painful.

Treatment

Long-term treatment is aimed at keeping blood from pooling in the veins around the ankles. When sitting, the person should elevate the legs above the level of the heart. Properly fitted prescription support hose (compression stockings) also prevent pooling of blood and decrease swelling. Department store "support" stockings are not adequate.

For dermatitis of recent onset, soothing compresses, such as gauze pads soaked in tap water or aluminum acetate (Burow's solution), may make the skin feel better and can help prevent infection by keeping the skin clean. If the disorder worsens, as evidenced by increased warmth, redness, small ulcers, or pus, a more absorbent dressing can be used. Corticosteroid creams are also helpful and are often combined with zinc oxide paste and applied in a thin layer. Corticosteroids should not be applied directly to an ulcer because this will interfere with healing.

When a person has large or extensive ulcers, special moisture-containing hydrocolloid or hydrogel dressings may be used. Antibiotics are used only when the skin is already infected. Sometimes, skin from elsewhere on the body may be grafted to cover very large ulcers.

Some people may need an Unna's boot, which is a woven stretch wrap filled with a gelatin paste that contains zinc. The wrap is applied to the ankle and lower leg where it hardens, similar to but softer than a cast. The boot limits swelling and helps protect the skin from irritation, and the paste helps heal the skin. At first the boot is changed every 2 or 3 days, but later it is left on for a week at a time.

In stasis dermatitis, the skin is easily irritated; antibiotic creams, first-aid (anesthetic) creams, alcohol, witch hazel, lanolin, or other chemicals should not be used because they can make the disorder worse.

Localized Scratch Dermatitis

Localized scratch dermatitis (lichen simplex chronicus, neurodermatitis) is chronic, itchy inflammation of the top layer of the skin.

Localized scratch dermatitis is caused by chronic scratching of an area of skin. The act of scratching triggers more itching, beginning a vicious circle of itching-scratching-itching. Sometimes the scratching begins for no apparent reason. Other times scratching starts because of a contact dermatitis, parasitic infestation, or other condition, but the person continues to scratch long after the inciting cause is gone. Doctors do not know why this happens, but psychologic factors may play a role. The disorder does not seem to be allergic. More women than men have localized scratch dermatitis, and it is common among Asians and Native Americans. It usually develops between the ages of 20 and 50.

Symptoms and Diagnosis

Localized scratch dermatitis can occur anywhere on the body, including the anus (pruritus ani and the vagina (pruritus vulvae, but is most common on the head, arms, and legs. In the early stages, the skin looks normal, but it itches. Later, dryness, scaling, and dark patches develop as a result of the scratching and rubbing.


Doctors try to discover any possible underlying allergies or diseases that may be causing the initial itching. When the disorder occurs around the anus or vagina, the doctor may investigate the possibility of pinworms, trichomoniasis, hemorrhoids, local discharges, fungal infections, warts, contact dermatitis, or psoriasis as the cause.

Treatment

For the disorder to clear up, the person must stop all scratching and rubbing of the area. Standard treatments for itching should be followed (see Itching and Noninfectious Rashes: Treatment). Using surgical tape saturated with a corticosteroid helps relieve itching and inflammation and protects the skin from scratching. The doctor may inject longer-acting corticosteroids under the skin to control the itching.

When this disorder develops around the anus or vagina, the best treatment is a corticosteroid cream. Zinc oxide paste may be applied over the cream to protect the area; the paste can be removed with mineral oil.

Perioral Dermatitis

Perioral dermatitis is a red, bumpy rash around the mouth and on the chin.

The disorder, whose cause is unknown, mainly affects women between the ages of 20 and 60.

Treatment is with tetracyclines or other antibiotics taken by mouth. If these antibiotics do not clear up the rash and the disorder is particularly severe, isotretinoin, an acne drug, may help. Corticosteroids and some oily cosmetics, especially moisturizers, tend to worsen the disorder.


Pompholyx
Pompholyx is a chronic dermatitis characterized by itchy blisters on the palms and sides of the fingers and sometimes on the soles of the feet.

Pompholyx is sometimes called dyshidrosis, which means "abnormal sweating," but the disorder has nothing to do with sweating. Doctors do not know what causes pompholyx, but stress may be a factor as well as some ingested substances such as nickel, chromium, and cobalt. It is more common in adolescents and young adults.

The blisters are often scaly, red, and oozing. Pompholyx comes and goes in attacks that last 2 to 3 weeks. Pompholyx takes weeks to go away on its own. Wet compresses with potassium permanganate or aluminum acetate (Burow's solution) may help the blisters resolve. Strong topical corticosteroids may help itching and inflammation.

Adapted from Merck & Co., Inc.

Ringworm, Tinea Versicolor

Rignworm
Ringworm (tinea) is a fungal skin infection caused by several different fungi and generally classified by its location on the body.

Despite its name, ringworm infection does not involve worms. The name arose because of the ring-shaped skin patches created by the infection.

Athlete's foot (tinea pedis) is a common fungal infection that usually appears during warm weather. The infection may spread from person to person in communal showers and bathrooms or in other moist areas where infected people walk barefoot. It is usually caused by either Trichophyton or Epidermophyton. These fungi most commonly grow in the warm, moist areas between the toes. The fungus can produce mild scaling with or without redness and itching. The scaling may involve a small area or the entire sole of the foot; sometimes even the toenails are involved. Sometimes scaling is severe, with breakdown and painful cracking (fissuring) of the skin. Fluid-filled blisters can also form. Because the fungus may cause the skin to crack, athlete's foot can lead to bacterial infection (see Bacterial Skin Infections: Introduction), especially in older people and in people with inadequate blood flow to the feet.


Nail ringworm (tinea unguium, onychomycosis is an infection of the nail most often caused by Trichophyton. The fungus may get into the nail, producing a thickened, lusterless, and deformed nail. Infection is much more common on the toenails than on the fingernails. An infected toenail may separate from the toenail bed, crumble, or flake off.

Jock itch (tinea cruris) is much more common in men than in women and develops most frequently in warm weather. The infection begins in the skinfolds of the genital area and can spread to the upper inner thighs. Usually the scrotum is not involved (unlike in yeast infection). The rash has a scaly, pink border. Jock itch can be quite itchy and may be painful. A susceptible person may have repeated infections.

Scalp ringworm (tinea capitis) is primarily caused by Trichophyton. Scalp ringworm is highly contagious and is common among children (see Problems in Infants and Very Young Children: Rashes), especially black children. It may produce a pink scaly rash that may be somewhat itchy, or it may produce a patch of hair loss without a rash. Less commonly it can cause a painful, inflamed, swollen patch on the scalp that sometimes oozes pus (a kerion). A kerion is caused by an allergic reaction to the fungus.

Body ringworm (tinea corporis) may be caused by Trichophyton, Microsporum, or Epidermophyton. The infection generally produces round patches with pink scaly borders and clear areas in the center. Sometimes the rash is itchy. Body ringworm can develop anywhere on the skin and can spread rapidly to other parts of the body or to other people with whom there is close bodily contact.

Beard ringworm (tinea barbae) is rare. Most skin infections in the beard area are caused by bacteria, not fungi.

Treatment

Most ringworm infections, except those of the scalp and nails, are mild. Antifungal creams usually cure them. Many effective antifungal creams can be purchased without a prescription; antifungal powders are generally not as good. The active ingredients in topical antifungal drugs include miconazole, clotrimazole, econazole, oxiconazole, ciclopirox, ketoconazole, terbinafine, and butenafine.

Usually, creams are applied once or twice a day, and treatment should continue for 7 to 10 days after the rash completely disappears. If the cream is discontinued too soon, the infection may not be eradicated, and the rash will return. Ciclopirox in the form of a nail lacquer may be painted on fungal nail infections. This treatment may take up to 1 year, however, and still may not be effective.

Several days may pass before antifungal creams reduce symptoms. Corticosteroid creams are often used to help relieve itching and pain for the first few days. Low-dose hydrocortisone is available over the counter; more potent corticosteroids require a prescription and may be added to the antifungal cream.

For more serious or stubborn skin infections and for scalp and nail infections, a doctor may prescribe an antifungal drug to be taken by mouth. Itraconazole, terbinafine, and griseofulvin are all effective. These drugs are taken daily. Some doctors prescribe fluconazole, which may be given once a week for 3 or 4 weeks for body ringworm. Nail ringworm requires longer treatment with itraconazole or terbinafine : 6 weeks for fingernails and 12 weeks or longer for toenails. Up to 1 year is required for new toenails to grow out. Terbinafine is the most effective drug available for treating nail ringworm. Griseofulvin requires more prolonged treatment. However, nail ringworm does not always respond to drugs taken by mouth and may recur even after apparently successful treatment. Scalp ringworm may need to be treated with drugs taken by mouth for 4 to 6 weeks—or even longer if griseofulvin is used. Some doctors give corticosteroids by mouth to children with a kerion of the scalp.

If the ringworm infection oozes, a bacterial infection also may have developed. Such an infection may require treatment with antibiotics, either applied to the skin or taken by mouth

Tinea Versicolor

Tinea versicolor (pityriasis versicolor) is a fungal infection of the topmost layer of the skin causing scaly, discolored patches.

The infection, caused by the yeast Malassezia furfur, is quite common, especially in young adults. It rarely causes pain or itching, but it prevents areas of the skin from tanning, producing patches that are lighter in color than surrounding skin. People with naturally dark skin may notice lighter patches; people with naturally fair skin may get dark or lighter patches. The color depends on how the yeast affect the melanocytes, the cells that make the pigment (see Pigment Disorders: Introduction). The patches are often on the chest or back and may scale slightly. Over time, small areas can join to form large patches.

Diagnosis and Treatment

Doctors can diagnose tinea versicolor by its appearance. A doctor may use an ultraviolet light to show the infection more clearly or may examine scrapings from the infected area under a microscope to confirm the diagnosis.

Topical antifungal cream such as ketoconazole may be used, as well as terbinafine
solution spray. Prescription selenium sulfide shampoo is effective if applied full-strength to the affected areas (including the scalp) at bedtime, left on overnight, and washed off in the morning. Treatment is usually continued for 3 or 4 nights. Alternatively, the shampoo can be applied for 10 minutes a day for 10 days. Prescription ketoconazole shampoo is also effective; it is applied and washed off in 5 minutes. It is used as a single application or daily for 3 days.

Antifungal drugs taken by mouth, such as itraconazole, ketoconazole, or fluconazole
, are sometimes used to treat widespread, resistant infection (see Drugs for Serious Fungal Infections). However, because these drugs may cause unwanted side effects, topical drugs are usually preferred.

The skin may not regain its normal pigmentation for many months after the infection is gone. Tinea versicolor commonly comes back after successful treatment because the fungus that causes it normally lives on the skin. Therefore, many doctors recommend use of 2.5% selenium sulfide shampoo or ketoconazole shampoo monthly or every other month to prevent recurrences.

Adapted from: Merck & Co., Inc

Fungal Skin Infections

Introduction
Fungi usually make their homes in moist areas of the body where skin surfaces meet: between the toes, in the genital area, and under the breasts. Many fungi that infect the skin (dermatophytes) live only in the topmost layer of the epidermis (stratum corneum) and do not penetrate deeper. Obese people are more likely to get these infections because they have excessive skinfolds. People with diabetes tend to be more susceptible to fungal infections as well.

Strangely, fungal infections on one part of the body can cause rashes on other parts of the body that are not infected. For example, a fungal infection on the foot may cause an itchy, bumpy rash on the fingers. These eruptions (dermatophytids, or id reactions) are allergic reactions to the fungus. They do not result from touching the infected area.

A doctor may suspect a fungal infection upon seeing a red, irritated, or scaly rash in one of the commonly affected areas. The doctor can usually confirm the diagnosis by scraping off a small amount of skin and having it examined under a microscope or placed in a culture medium that will grow the specific fungus so that it can be identified (see Diagnosis and Treatment of Skin Disorders: Diagnosis).


Candidiasis
Candidiasis (yeast infection, moniliasis) is infection by the yeast Candida, formerly called Monilia.

Candida is a normal resident of the mouth, digestive tract, and vagina that usually causes no harm. Under certain conditions, however, Candida can infect mucous membranes and moist areas of the skin. Typical areas of infection are the lining of the mouth and vagina, the genital area and anus, the armpits, the skin under the breasts in women, and the skinfolds of the stomach. Conditions that enable Candida to infect the skin include hot, humid weather; tight, synthetic underclothing; poor hygiene; and inflammatory diseases, such as psoriasis, occurring in the skinfolds.

People taking antibiotics may develop candidiasis because the antibiotics kill the bacteria that normally reside on the body, allowing Candida to grow unchecked. Corticosteroids or immunosuppressive therapy after organ transplantation can also lower the body's defenses against candidiasis. Inhaled corticosteroids, often used by people with asthma, sometimes produce candidiasis of the mouth. Pregnant women, obese people, and people with diabetes also are more likely to be infected by Candida.

In some people (usually people with a weakened immune system), Candida invades deeper tissues as well as the blood, causing life-threatening systemic candidiasis

Symptoms

Symptoms vary, depending on the location of the infection.

Infections in skinfolds (intertriginous infections) or in the navel usually cause a bright red rash, sometimes with softening and breakdown of skin. Small pustules may appear, especially at the edges of the rash, and the rash may itch intensely or burn. A Candida rash around the anus may be raw, white or red, and itchy. Babies may develop a Candida rash in the diaper area (see Problems in Infants and Very Young Children: Rashes).

Vaginal candidiasis (vulvovaginitis, yeast infection (see Vaginal Infections) is common, especially in women who are pregnant, have diabetes, or are taking antibiotics. Symptoms of these infections include a white or yellow cheeselike discharge from the vagina and burning, itching, and redness along the walls and external area of the vagina.

Penile candidiasis most often affects men with diabetes, uncircumcised men, or men whose female sex partners have vaginal candidiasis. Usually the infection produces a red, raw, sometimes painful rash on the head of the penis and sometimes the scrotum. Sometimes the rash may not cause any symptoms.

Thrush is candidiasis inside the mouth (see Periodontal Diseases: Gingivitis due to Infections). The creamy white patches typical of thrush cling to the tongue and sides of the mouth and may be painful. The patches cannot be scraped off easily with a finger or blunt object. Thrush in otherwise healthy children is not unusual, but in adults it may signal a weakened immune system, possibly caused by diabetes or AIDS. The use of antibiotics that kill off competing bacteria increases the chances of getting thrush.

Perlèche is candidiasis at the corners of the mouth, creating cracks and tiny cuts. It may stem from chronic lip licking, thumb sucking, ill-fitting dentures, or any other condition that leaves the corners of the mouth moist enough so that yeast can grow.

Candidal paronychia is candidiasis in the nail beds, producing painful redness and swelling (see Foot Problems: Onychomycosis). Nails infected with Candida may turn white or yellow and separate from the nail bed. This disorder typically occurs in people with diabetes or a weakened immune system or in otherwise healthy people whose hands are subjected to frequent wetting or washing.

Diagnosis and Treatment

Usually, a doctor can identify candidiasis by observing its distinctive rash or the thick, white, pasty residue it generates. To confirm the diagnosis, a doctor may scrape off some of the skin or residue with a scalpel or tongue depressor. The sample is then examined under a microscope or placed in a culture medium (a substance that allows microorganisms to grow) to identify the specific fungus.

Generally, candidiasis of the skin is easily cured with creams containing miconazole
, clotrimazole, oxiconazole, ketoconazole, econazole, ciclopirox, or nystatin . The cream is usually applied twice daily for 7 to 10 days. Corticosteroid creams are sometimes used along with antifungal creams because they quickly reduce itching and pain (although they do not help cure the infection itself). Candidiasis that does not respond to antifungal creams and liquids may be treated with gentian violet, a purple dye that is painted on the infected area to kill the yeast.

Keeping the skin dry helps clear up the infection and prevents it from returning. Talcum powder helps keep the surface area dry, and talcum powder with nystatin may further help prevent a recurrence.

Different treatments are prescribed for vaginal yeast infections, thrush, and nail infections.

Adapted from: Merck & Co., Inc

Skin Blistering Diseases

Introduction
A blister (bulla) is a bubble of fluid that forms beneath a thin layer of dead skin. The fluid is a mixture of water and proteins that oozes from injured tissue. Blisters most commonly form in response to a specific injury, such as a burn or irritation, and usually involve only the topmost layers of skin. These blisters heal quickly, usually without leaving a scar. Blisters that develop as part of a systemic (bodywide) disease may start in the deeper layers of the skin and cover widespread areas. These blisters heal more slowly and may leave scars.

Many diseases and injuries can cause blistering, but three autoimmune diseases—pemphigus, bullous pemphigoid, and dermatitis herpetiformis—are among the most serious. In an autoimmune disease, the body's immune system, which normally protects the body against foreign invaders, mistakenly attacks the body's own cells (see Autoimmune Disorders)—in this case, the skin.

Bullous pemphigoid
Bullous pemphigoid is an autoimmune disease that causes blistering of the skin.

Bullous pemphigoid tends to occur mainly in older people. It is a less serious disease than pemphigus, is rarely fatal, and does not result in widespread peeling of skin. It can involve a large portion of the skin, however, and can be very uncomfortable.

In bullous pemphigoid, the immune system forms antibodies directed against the skin, resulting in large, tense, very itchy blisters surrounded by areas of red, inflamed skin. Blisters in the mouth are uncommon and are not severe. The areas of skin that are not blistered appear normal.

Diagnosis and Treatment

Doctors usually recognize bullous pemphigoid by its characteristic blisters. However, it is not always easy to distinguish from pemphigus and other blistering conditions, such as severe poison ivy; it is diagnosed with certainty by examining a sample of skin under a microscope (skin biopsy). Doctors differentiate bullous pemphigoid from pemphigus by noting the layers of skin involved and the particular appearance of the antibody deposits.

Mild bullous pemphigoid sometimes resolves without treatment, but resolution usually takes months or years. Therefore, most people receive drug therapy. Nearly everyone responds quickly to high-dose corticosteroids, which are tapered after several weeks. Sometimes azathioprine or cyclophosphamide is given as well. Immune globulin given intravenously is a safe, promising new treatment, especially for people who do not respond to conventional drug therapy. Although some local skin care may be needed, most people do not require hospitalization or intensive skin care treatment.

Dermatitis Herpetiformis
Dermatitis herpetiformis is an autoimmune disease causing clusters of intensely itchy small blisters and hivelike swellings.

Despite its name, dermatitis herpetiformis has nothing to do with the herpes virus. In people with dermatitis herpetiformis, glutens (proteins) in wheat, rye, and barley products somehow activate the immune system, which attacks parts of the skin and causes the rash and itching. People with dermatitis herpetiformis may develop celiac disease, which is caused by the gluten sensitivity. These people have a higher incidence of other autoimmune diseases, such as thyroiditis, systemic lupus erythematosus, sarcoidosis, and diabetes. People with dermatitis herpetiformis occasionally develop lymphoma in the intestines.

Small blisters usually develop gradually, mostly on the elbows, knees, buttocks, lower back, and back of the head. Sometimes blisters break out on the face and neck. Itching and burning are likely to be severe. Anti-inflammatory drugs, such as ibuprofen , may worsen the rash.

Diagnosis and Treatment

The diagnosis is based on a skin biopsy, in which doctors find particular kinds and patterns of antibodies in the skin samples.

The blisters do not go away without treatment. The drug dapsone, taken by mouth, almost always provides relief in 1 to 2 days, but requires that blood counts be checked regularly. Once the disease has been brought under control with drugs and the person has followed a strict gluten-free diet (a diet that is free of wheat, rye, and barley) for 6 months or longer, drug treatment usually can be discontinued. However, some people can never discontinue the drug. In most people, any reexposure to gluten, however small, will trigger another outbreak. A gluten-free diet may prevent the development of intestinal lymphoma.


Pemphigus
Pemphigus (pemphigus vulgaris) is a rare, severe autoimmune disease in which blisters of varying sizes break out on the skin, the lining of the mouth, the genitals, and other mucous membranes.

Pemphigus develops most often in middle-aged or older people. It rarely develops in children. In this disease, the immune system produces antibodies that attack specific proteins that connect the epidermal cells (the cells in the top layer of skin) to each other. When these connections are disrupted, the cells separate from the lower layers of the skin, and blisters form. A similar-appearing but less dangerous disease, bullous pemphigoid, results in shallower blisters.

Symptoms

The major symptom of pemphigus is the development of clear, soft, painful blisters of various sizes. In addition, the top layer of skin may detach from the lower layers in response to slight pinching or rubbing, causing it to peel off in sheets.

The blisters that develop often first appear in the mouth and soon rupture, forming painful ulcers (sores). More blisters and ulcers may follow until the entire lining of the mouth is affected, causing difficulty swallowing. Blisters form on the skin as well. These blisters then rupture, leaving raw, painful, crusted wounds. The person feels generally ill. Blisters may be widespread, and once ruptured, they may become infected. When severe, pemphigus is as harmful as a serious burn. Similar to a burn, the damaged skin oozes large amounts of fluid and is prone to infection by many types of bacteria.

Diagnosis and Treatment

Doctors usually recognize pemphigus by its characteristic blisters, but the disorder is diagnosed with certainty by examining a sample of skin under a microscope (skin biopsy). Sometimes doctors use special chemical stains that allow antibody deposits to be seen under the microscope. Doctors differentiate pemphigus from bullous pemphigoid by noting the layers of skin involved and the particular appearance of the antibody deposits.

Without treatment, pemphigus is usually fatal. With treatment, 90% of people with pemphigus survive. High doses of corticosteroids are the mainstay of treatment. If the disease is controlled, the dose of corticosteroids is tapered. If the person does not respond to treatment or the disease flares up as the dose is tapered, an immunosuppressant, such as azathioprine or cyclophosphamide, is also given. People with severe pemphigus may also undergo plasmapheresis, a process in which antibodies are filtered from the blood. Injections of gold salts are sometimes used. Immune globulin given intravenously is a new, safe and effective treatment for severe pemphigus. Some people respond well enough to discontinue drug therapy, whereas others must continue taking low doses of the drugs for long periods.

In a hospital, the raw skin surfaces require extraordinary care, similar to the care given to people with severe burns. Antibiotics may be needed to treat infections in ruptured blisters. Dressings, sometimes filled with petroleum jelly, can protect raw, oozing areas.

Adapted from: Merck & Co., Inc

NSI, Staphylococcal Scalded Skin Syndrome

Necrotizing Skin Infections(NSI), including necrotizing cellulitis and necrotizing fasciitis, are severe forms of cellulitis characterized by death of infected tissue (necrosis).

Most skin infections do not result in death of skin and nearby tissues. Sometimes, however, bacterial infection can cause small blood vessels in the infected area to clot. This clotting causes the tissue fed by these vessels to die from lack of blood. Because the body's immune defenses that travel through the bloodstream (such as white blood cells and antibodies) can no longer reach this area, the infection spreads rapidly and may be difficult to control. Death is not uncommon, even with appropriate treatment.

Some necrotizing skin infections spread deep in the skin along the surface of the muscle (fascia) and are termed necrotizing fasciitis. Other necrotizing skin infections spread on the outer layers of skin and are termed necrotizing cellulitis. Several different bacteria, such as Streptococcus and Clostridia, may cause necrotizing skin infections, although in many people the infection is caused by a combination of bacteria. The streptococcal infection in particular has been termed "flesh-eating disease" by the lay press, although it differs little from the others.

Some necrotizing skin infections begin at puncture wounds or lacerations, particularly wounds contaminated with dirt and debris. Other infections begin in surgical incisions or even healthy skin. Sometimes people with diverticulitis, intestinal perforation, or tumors of the intestine develop necrotizing infections of the abdominal wall, genital area, or thighs. These infections occur when certain bacteria escape from the intestine and spread to the skin. The bacteria may initially create an abscess in the abdominal cavity and spread directly outward to the skin, or they may spread through the bloodstream to the skin and other organs.

Symptoms and Diagnosis

Symptoms often begin just as for cellulitis. The skin may look pale at first, but quickly becomes red or bronze and warm to the touch, and sometimes becomes swollen. Later, the skin turns violet, often with the development of large fluid-filled blisters (bullae). The fluid from these blisters is brown, watery, and sometimes foul smelling. Areas of dead skin (gangrene) turn black. Some types of infection, including those produced by Clostridia and mixed bacteria, produce gas. The gas creates bubbles under the skin and sometimes in the blisters themselves, causing the skin to feel crackly when pressed. Initially the infected area is painful, but as the skin dies, the nerves stop working and the area loses sensation.

The person usually feels very ill and has a fever, a rapid heart rate, and mental deterioration ranging from confusion to unconsciousness. Blood pressure may fall because of toxins secreted by the bacteria and the body's response to the infection (septic shock ).

A doctor makes a diagnosis of necrotizing skin infection based on its appearance, particularly the presence of gas bubbles under the skin. X-rays may show gas under the skin as well. The specific bacteria involved are identified by laboratory analysis of infected fluid and tissue samples. However, treatment must begin before a doctor can be certain which bacteria are causing the infection.

Treatment and Prognosis

The treatment for necrotizing fasciitis is intravenous antibiotic therapy and surgical removal of the dead tissue. Large amounts of skin, tissue, and muscle must often be removed, and in some cases, an affected arm or leg may have to be amputated. People with necrotizing infections caused by anaerobic bacteria (for example, Clostridium perfringens may benefit from treatment in a high-pressure (hyperbaric) oxygen chamber.

The overall death rate is about 30%. Older people, those who have other medical disorders, and those in whom the disease has reached an advanced stage have a poorer outcome.

Staphylococcal Scalded Skin Syndrome

Staphylococcal scalded skin syndrome is a reaction to a staphylococcal skin infection in which the skin peels off as though burned.

Certain types of staphylococci bacteria secrete toxic substances that cause the top layer of the epidermis to split from the rest of the skin. Because the toxin spreads throughout the body, staphylococcal infection of a small area of skin may result in peeling over the entire body. Staphylococcal scalded skin syndrome occurs almost exclusively in infants, young children, and people with a weakened immune system. Like other staphylococcal infections, staphylococcal scalded skin syndrome is contagious.

Symptoms

Symptoms begin with an isolated, crusted infection that may look like impetigo. In newborns, the infection may appear in the diaper area or around the stump of the umbilical cord. In adults, the infection may begin anywhere. In all people with this disorder, scarlet-colored areas appear around the crusted area within a day of the beginning of infection. These areas may be painful. Then, other large areas of skin distant from the initial infection redden and develop blisters that break easily.

The top layer of the skin then begins peeling off, often in large sheets, with even slight touching or gentle pushing. Within another 1 to 2 days, the entire skin surface may be involved, and the person becomes very ill with a fever, chills, and weakness. With the loss of the protective skin barrier, other bacteria and infective organisms can easily penetrate the body, causing what doctors call superinfections. Also, critical amounts of fluid can be lost because of oozing and evaporation, resulting in dehydration.

Diagnosis and Treatment

A diagnosis is made by the appearance of skin peeling after an apparent staphylococcal infection. If no signs of staphylococcal infection are observed, doctors often perform a biopsy, in which a small piece of skin is removed, examined under a microscope, and sent to the laboratory to be cultured for bacteria.

Antibiotics given intravenously, such as nafcillin or cefazolin , are started quickly. Treatment continues for at least 10 days. With early treatment, healing takes 5 to 7 days.

The skin must be protected to help prevent further peeling; it should be treated as if it were burned

Adapted from: Merck & Co., Inc

Hidradenitis Suppurativa , Impetigo

Hidradenitis Suppurativa
Hidradenitis suppurativa is inflammation of the apocrine sweat glands resulting in painful accumulations of pus under the skin.

Hidradenitis suppurativa develops in some people after puberty because of chronic blockage of the apocrine sweat glands (the specialized sweat glands under the arms, in the genital area, around the anus, and under the breasts). Doctors do not know why the blockage occurs, but it is not related to the use of deodorants or powders or to underarm shaving. The blockage causes the glands to swell and rupture, frequently leading to infection by various bacteria. The abscesses (pus-filled pockets) that result are painful and foul smelling and tend to recur. After several recurrences, the skin in the area becomes thick and scarred.

Hidradenitis suppurativa resembles common skin abscesses. A doctor makes the diagnosis based on the location of the abscesses and on the fact that they recur often.

For people with mild cases, a doctor injects corticosteroids into the area and prescribes antibiotics, such as tetracycline or erythromycin , to be taken by mouth. Clindamycin applied topically is also effective. In some cases, a doctor cuts open the abscesses to drain the pus. For severe cases, isotretinoin , an anti-inflammatory drug, may be given by mouth. Laser treatment has also been used. In severe cases, cutting out the involved area followed by skin grafting may be necessary.


Impetigo

Impetigo is a skin infection, caused by Staphylococcus aureus, Streptococcus pyogenes, or both, that leads to the formation of scabby, yellow-crusted sores and, sometimes, small blisters filled with yellow fluid.

Impetigo is common. It affects mostly children. Impetigo can occur anywhere on the body but most commonly occurs on the face, arms, and legs. The blisters that may form (bullous impetigo) can vary from pea-sized to large rings and can last for days to weeks. Impetigo often affects normal skin but may follow an injury or a condition that causes a break in the skin, such as a fungal infection, sunburn, or an insect bite.

Impetigo is itchy and slightly painful. The itching often leads to extensive scratching, particularly in children, which serves to spread the infection. Impetigo is very contagious—both to other areas of the person's own skin and to other people.

The infected area should be washed gently with soap and water several times a day to remove any crusts. Small areas are treated with bacitracin ointment or mupirocin cream or ointment. If large areas are involved, an antibiotic taken by mouth, such as a cephalosporin, may be needed.

Adapted from: Merck & Co., Inc

Erythrasma

Erythrasma is infection of the top layers of the skin caused by the bacterium Corynebacterium minutissimum.

Erythrasma affects mostly adults, especially those with diabetes; it is most common in the tropics. Erythrasma often appears in areas where skin touches skin, such as under the breasts and in the armpits, webs of the toes, and genital area—especially in men, where the thighs touch the scrotum. The infection can produce irregularly shaped pink patches that may later turn into fine brown scales. In some people, the infection spreads to the torso and anal area.

Although erythrasma may be confused with a fungal infection, doctors can easily diagnose erythrasma because skin infected with Corynebacterium glows coral red under an ultraviolet light.

An antibiotic given by mouth, such as erythromycin or tetracycline , can eliminate the infection. Antibacterial soaps, such as chlorhexidine, may also help. Topical drugs such as clindamycin and miconazole cream are also effective. Erythrasma may recur in 6 to 12 months, necessitating a second treatment.


Folliculitis, Skin Abscesses, and Carbuncles
Folliculitis, skin abscesses, and carbuncles are pus-filled pockets in the skin resulting from bacterial infection.

Most skin infections involving pus-filled pockets are caused by Staphylococcus aureus bacteria (see Bacterial Infections: Staphylococcal Infections). Sometimes the bacteria enter the skin through a hair follicle, small scrape, or puncture, although often there is no obvious point of entry. People who have poor hygiene or chronic skin diseases or whose nasal passages contain Staphylococcus are more likely to have episodes of these skin infections. Some people may have recurring episodes of infection for unknown reasons.

Doctors may try to eliminate Staphylococcus from people prone to recurring infections by instructing them to wash the entire body with antibacterial soap, apply antibiotic ointment inside the nose, and take antibiotics by mouth.

Folliculitis, skin abscesses, and carbuncles differ in the size and depth of the pus-filled pockets.

Folliculitis: Folliculitis is an infection of a hair follicle. It looks like a tiny white pimple at the base of a hair. There may be only one infected follicle or many. Each infected follicle is slightly painful, but the person otherwise does not feel sick.

Some people develop folliculitis after exposure to a poorly chlorinated hot tub or whirlpool. This condition, sometimes called "hot-tub folliculitis" or "hot-tub dermatitis," is caused by the bacterium Pseudomonas aeruginosa. It begins anytime from 6 hours to 5 days after the exposure. Areas of skin covered by a bathing suit, such as the torso and buttocks, are the most common sites.

Sometimes stiff hairs in the beard area curl and reenter the skin (ingrown hair) after shaving, producing irritation without substantial infection. This type of folliculitis (pseudofolliculitis barbae) is particularly common in black men.

Folliculitis is treated with warm compresses. Sometimes, topical antibiotics with mupirocin or clindamycin are applied 2 to 3 times per day. Large areas of folliculitis may require antibiotics, such as dicloxacillin or cephalexin , taken by mouth. Hot-tub folliculitis goes away in a week without any treatment. Folliculitis caused by ingrown hairs is treated by a number of methods with varying success. For severe, recurring problems, shaving may need to be discontinued.

Skin Abscesses: Skin abscesses, also called boils or furuncles, are warm, painful pus-filled pockets of infection below the skin surface. Abscesses may be from one to several inches in diameter. If not treated, they often come to a point and rupture. Bacteria may spread from the abscess to infect the surrounding tissue and lymph nodes. The person may have a fever and feel generally sick.

A doctor treats an abscess by cutting it open and draining the pus. After draining the abscess, a doctor makes sure all of the pus has been removed by washing out the pocket with a sterile salt solution. Sometimes the drained abscess is packed with gauze, which is removed 24 to 48 hours later.

If the abscess is completely drained, antibiotics usually are not needed. However, if the infection has spread or if the abscess is on the middle or upper part of the face, antibiotics that kill staphylococci, such as dicloxacillin and cephalexin, may be used because of the high risk that the infection will spread to the brain.

Carbuncles: Carbuncles are clusters of small, shallow abscesses that connect with each other under the skin. Multiple areas may open and drain pus spontaneously. The person often has a fever and feels fatigued and sick. Carbuncles are more common in men and usually occur on the back of the neck. They often result in extensive peeling of skin and scar formation. Older people, people with diabetes, and people with serious medical disorders are more prone to carbuncles.

Treatment is with antibiotics taken by mouth. Any large abscesses are cut open to allow pus to drain. Carbuncles are hard to eliminate because many small pus-filled pockets are difficult to find and drain. Therefore, antibiotics must sometimes be continued for several months.

Adapted from: Merck & Co., Inc

Bacterial Skin Infections

Introduction
The skin provides a remarkably good barrier against bacterial infections. Although many bacteria come in contact with or reside on the skin, they are normally unable to establish an infection. When bacterial skin infections do occur, they can range in size from a tiny spot to the entire body surface. They can range in seriousness as well, from harmless to life threatening.

Many types of bacteria can infect the skin. The most common are Staphylococcus and Streptococcus. Skin infections caused by less common bacteria may develop in hospitals or nursing homes or while gardening or swimming in a pond, lake, or ocean.

Some people are at particular risk of contracting skin infections—for example, people with diabetes because they are likely to have poor blood flow, especially to the hands and feet, and because high levels of sugar in the blood decrease the ability of white blood cells to fight infections. People with AIDS or other immune disorders and those undergoing chemotherapy are at higher risk as well, because they have a weakened immune system. Skin that is inflamed or damaged by sunburn, scratching, or other trauma is more likely to be infected. In fact, any break in the skin predisposes a person to infection.

Prevention involves keeping the skin undamaged and clean. When the skin is cut or scraped, the injury should be washed with soap and water and covered with a sterile bandage. Antibiotic creams and ointments may be applied to open areas to keep the tissue moist and to try to prevent bacterial invasion. If an infection develops, small areas may be treated with antibiotic creams. Larger areas require antibiotics taken by mouth or given by injection. Abscesses (pus-filled pockets) should be cut open by the doctor and allowed to drain, and any dead tissue must be surgically removed.

Cellulitis
Cellulitis is a spreading bacterial infection of the skin and the tissues immediately beneath the skin.

Cellulitis may be caused by many different bacteria; the most common are those of the Streptococcus species. Streptococci spread rapidly in the skin because they produce enzymes that hinder the ability of the tissue to confine the infection. Staphylococcus bacteria can also cause cellulitis, as can many other bacteria, especially after bites by humans or animals or after injuries in water or dirt.

Bacteria usually enter through small breaks in the epidermis that result from scrapes, punctures, burns, and skin disorders such as dermatitis. Areas of the skin that become swollen with fluid (edema) are especially vulnerable. However, cellulitis can also occur in skin that is not overtly injured.

Symptoms and Complications

Cellulitis most commonly develops on the legs but can occur anywhere. The first symptoms are redness, pain, and tenderness over an area of skin. These symptoms are caused both by the bacteria themselves and by the body's attempts to halt the infection. The infected skin becomes hot and slightly swollen and may look slightly pitted, like an orange peel. Fluid-filled blisters, which may be small (vesicles) or large (bullae), sometimes appear on the infected skin. Erysipelas is one form of streptococcal cellulitis in which the skin is bright red and noticeably swollen and the edges of the infected area are raised. The swelling occurs because the infection blocks the lymphatic vessels in the skin.

Most people with cellulitis feel only mildly ill, but some may have a fever, chills, rapid heart rate, headache, low blood pressure, and confusion.

As the infection spreads, nearby lymph nodes may become enlarged and tender (lymphadenitis). Other complications—lymphangitis, skin abscesses, and spread through the blood (sepsis) are also possible.

When cellulitis affects the same site repeatedly, especially the leg, lymphatic vessels may be damaged, causing permanent swelling of the affected tissue.

Diagnosis and Treatment

A doctor usually diagnoses cellulitis based on its appearance and symptoms. Laboratory identification of the bacteria from blood, pus, or tissue specimens usually is not necessary unless a person is seriously ill. Sometimes, doctors need to perform tests to differentiate cellulitis from a blood clot in the deep veins of the leg (deep vein thrombosis), because the symptoms of these disorders are similar.

Prompt treatment with antibiotics can prevent the infection from spreading rapidly and reaching the blood and organs. Antibiotics, such as dicloxacillin, that are effective against both streptococci and staphylococci are used. People with mild cellulitis may take antibiotics by mouth; those with rapidly spreading cellulitis, high fever, or other evidence of serious infection often receive intravenous antibiotics. Also, the affected part of the body, when possible, is kept immobile and elevated to help reduce swelling. Cool, wet dressings applied to the infected area may relieve discomfort.

Symptoms of cellulitis usually disappear after a few days of antibiotic therapy. However, symptoms often get worse before they get better, probably because with the death of the bacteria, substances that cause tissue damage are released. When this occurs, the body continues to react even though the bacteria are dead. Antibiotics are continued for 10 days or longer even though the symptoms may disappear earlier.

Adapted from: Merck & Co., Inc