(See also Overview of Fungal Skin Infections.)
Candida is a yeast that normally resides on the skin and in the mouth, digestive tract, and vagina and usually causes no harm. Under certain conditions, however, Candida can overgrow on mucous membranes and moist areas of the skin. Typical areas affected are the lining of the mouth, the groin, the armpits, the spaces between fingers and toes, on an uncircumcised penis, the skinfold under the breasts, the nails, and the skinfolds of the stomach. Yeast is a type of fungus.
Conditions that enable Candida to infect the skin include the following:
Hot, humid weather
Tight, synthetic underclothing
Infrequent diaper or undergarment changes, particularly in children and older people
A weakened immune system resulting from diabetes, HIV infection/AIDS, or use of corticosteroids and other drugs that suppress the immune system
Pregnancy, obesity, or use of antibiotics
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 cause candidiasis of the mouth. Pregnant women, people receiving cancer therapy drugs, 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 may invade deeper tissues as well as the blood, causing life-threatening systemic candidiasis.
Symptoms of candidiasis 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 breakdown of skin. Small pustules may appear, especially at the edges of the rash, and the rash may itch intensely or burn. A candidal rash around the anus may be raw, white or red, and itchy. Infants may develop a candidal diaper rash in the diaper area.
Vaginal candidiasis (vulvovaginitis, yeast infection—see Overview of Vaginal Infections) is common, especially among 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. Sometimes the rash may not cause any symptoms, but usually the infection causes a red, raw, itching, burning, or sometimes painful rash on the head of the penis.
Thrush is candidiasis inside the mouth. The creamy white patches typical of thrush cling to the tongue and sides of the mouth and may be painful. The patches can be scraped off with a finger or blunt object and may bleed when scraped. Thrush in otherwise healthy children is not unusual, but in adults it may signal a weakened immune system, possibly caused by cancer, diabetes, or human immunodeficiency virus (HIV) infection. The use of antibiotics that kill off competing bacteria increases the risk of developing thrush.
Perlèche is candidiasis at the corners of the mouth, which causes cracks and tiny fissures. It may stem from chronic lip licking, thumb sucking, ill-fitting dentures, or other conditions that make the corners of the mouth moist enough that yeast can grow.
Candidal paronychia is candidiasis in the nail folds or cuticles, which causes painful redness and swelling (see Onychomycosis) around the nail. In longstanding infection, the area underneath the nail may turn white or yellow, and the nail plate may separate from the nail bed (onycholysis). 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.
Chronic mucocutaneous candidiasis causes red, pus-filled, crusted, and thickened areas that resemble psoriasis, especially on the nose and forehead. People who have this condition are also prone to thrush.
Usually, doctors can identify candidiasis by observing its distinctive rash or the thick, white, pasty residue it generates.
Treatment of candidiasis typically depends on the location of the infection. (See also table Some Antifungal Drugs Applied to the Skin (Topical Drugs).)
Infections in skinfolds are treated with antifungal creams, powders, solutions, or other products that are applied directly to the skin (topical). Examples include miconazole, clotrimazole, oxiconazole, ketoconazole, econazole, ciclopirox, and nystatin. In healthy people, skinfold infections are usually easily cured. Keeping the skin dry helps clear up the infection and prevents it from returning. Solutions that dry out the skin (such as Burow solution) or topical antiperspirants help keep the surface area dry. Keeping the area dry may also help prevent a recurrence. People who have many infected skinfolds may be given drugs by mouth (such as fluconazole).
Vaginal candidiasis is treated with antifungal drugs that may be applied as a cream to the affected area, inserted into the vagina as a suppository, or taken by mouth (such as fluconazole).
Diaper rash is treated with more frequent changes of diapers, use of super-absorbent or ultra-absorbent disposable diapers, and a cream that contains an antifungal drug (for example, butoconazole, clotrimazole, fluconazole, ketoconazole, or miconazole).
Candidal paronychia is treated by protecting the area from wetness. Doctors give antifungal drugs that are taken by mouth or applied to the skin. These infections are often difficult to treat.
Thrush in adults is treated with drugs that go directly in the mouth. An antifungal drug (such as clotrimazole) may be given as a tablet or lozenge that dissolves in the mouth. Doctors may also have people gargle with liquid nystatin for as long as possible and then spit it out or swallow it. Doctors may also give drugs in pill form that are swallowed (such as fluconazole).
Thrush in infants may be treated with liquid nystatin. The liquid can be applied with a finger or cotton swab to the cheek pouches inside the mouth.
Chronic mucocutaneous candidiasis is treated with fluconazole taken by mouth. This drug is taken for a long time.