- Rash is not a specific diagnosis. Instead it means skin inflammation and discoloration that changes the way the skin looks.
- Common rashes include eczema, poison ivy, hives, and heat rash.
- Infections that cause rashes may be fungal, bacterial, parasitic, or viral.
- Over-the-counter products may be helpful treatments for many skin rashes.
- Rashes lasting more than a few days that are unexplained should be evaluated by a doctor.
What are the causes, symptoms, and signs of common noninfectious rashes?
Some common, noninfectious rashes are listed below. If you have a new rash and you have a fever or some other generalized illness associated with it, it would be best to see your doctor.
Seborrheic dermatitis: Seborrheic dermatitis is the single most common rash affecting adults. It produces a red scaling eruption that characteristically affects the scalp, forehead, brows, cheeks, and external ears.
Atopic dermatitis: Atopic dermatitis, often called eczema, is a common disorder of childhood which produces red itchy, weeping rashes on the inner aspects of the elbows and in back of the knees as well as the cheeks, neck, wrists, and ankles. It is commonly found in patients who also have asthma and hay fever.
Contact dermatitis: Contact dermatitis is a rash that is brought on either by contact with a specific chemical to which the patient is uniquely allergic or with a substance that directly irritates the skin. Some chemicals are both irritants and allergens. This rash is also occasionally weepy and oozy and affects the parts of the skin which have come in direct contact with the offending substance. Common examples of contact dermatitis caused by allergy are poison ivy or poison oak (same chemical, different plant) and reactions to costume jewelry containing nickel.
Diaper rash: This is a common type of contact dermatitis that occurs in most infants who wear diapers when feces and urine are in contact with skin for too long.
Stasis dermatitis: This is a weepy, oozy dermatitis that occurs on the lower legs of individuals who have chronic swelling because of poor circulation in veins.
Psoriasis: This bumpy scaling eruption never weeps or oozes and tends to occur on the scalp, elbows, and knees. It leads to silvery flakes of skin that scale and fall off.
Nummular eczema: This is a weepy, oozy dermatitis that tends to occur as coin-shaped plaques in the wintertime and is associated with very dry skin.
Drug eruptions: Certain drugs can produce skin rash as an unwanted side effect. The common appearance is similar to rashes produced by certain common viral infections. On the other hand, drugs may produce a wide variety of other types of rashes.
Viral rash: Certain viral infections, like herpes or shingles (a cousin of chickenpox), are mostly localized to one part of the body, other viral rashes are more often symmetrical and affect much of the skin surface. Patients with such rashes may or may not have other viral symptoms like coughing, sneezing, or stomach upset (nausea). Viral rashes usually last a few days to two weeks and go way on their own.
Hives: These red itchy bumps come on very quickly and then resolve in about eight hours. They tend to recur frequently.
Heat rash (miliaria): This skin eruption is caused by the occlusion of sweat ducts during hot, humid weather. It can occur at any age but is most common in infants who are kept too warm. Heat rash looks like a red cluster of pimples or small blisters. It is more likely to occur on the neck and upper chest, in the groin, under the breasts, and in elbow creases. Treatment involves moving the individual to a cooler environment.
Rashes not caused by infectious organisms, can be treated with over-the-counter 1% hydrocortisone cream for a week or so prior to seeking medical attention. Over-the-counter oral antihistamines like diphenhydramine (Benadryl) or hydroxyzine (Vistaril, Atarax) can be helpful in controlling the itching sensation.