A rash is a change in the color or texture of the skin that may involve swelling, blister-like eruptions and itching. The most common types of rashes are described below.
Atopic dermatitis, also known as eczema, is a red, itchy rash that occurs most often in children. It typically develops on the backs of the knees, on the inner elbows, and in the creases of neck, cheeks, wrists, and ankles. Contact with cleansers, detergents, wool and other irritants can make it worse. The rash tends to come and go throughout childhood and resolve with age but sometimes continues into adulthood. Many people with atopic dermatitis have hay fever or asthma as well, which suggests that an allergy is involved.
Contact dermatitis is an inflammation of the skin caused by contact with something that irritates the skin or triggers an allergic reaction in the skin. The rash is usually intensely itchy. Poison ivy is probably the most familiar contact dermatitis. Diaper rash is a form of contact dermatitis caused by urine or feces held against the skin by diapers. Allergic contact dermatitis can develop even after years of problem-free exposure to a product. A good example is a rash caused by contact with nickel jewelry. Other common irritants that can cause contact dermatitis include latex, cosmetics, detergents, dyes and topical medications.
Seborrheic dermatitis causes red, oily skin with greasy white or yellow flakes. It usually affects the skin on the scalp, behind the ears and around the mouth, nose, eyebrows, and eyelids. It is the result of excess secretions by the sebaceous glands, which produce an oily substance called sebum. When it occurs on the scalp in adults, it is called dandruff; in children, it is called cradle cap. Alcohol-based lotions, stress and even weather changes can make it worse.
Stasis dermatitis is a weepy rash that occurs on the lower legs when fluid accumulates beneath the surface of the skin and creates pressure against the skin from within. “Stasis” means “stagnation,” or poor circulation, of the blood. Conditions that can lead to stasis dermatitis include varicose veins, blood clots in the veins of the legs, pregnancy and extreme obesity.
Psoriasis produces red or pink patches with silvery scales, most commonly on the scalp, the tops of the knees, the backs of the elbows, the palms and the soles of the feet. The rash may itch, ache or burn. Psoriasis is a lifelong condition. Stress, skin damage and cold weather can trigger outbreaks, but it can worsen for no apparent reason. Approximately 30 percent of patients with psoriasis develop psoriatic arthritis as well.