Prickly Heat

Miliaria rubra, commonly known as "prickly heat," is an inflammatory skin disorder caused by the blockage of sweat ducts. Such blockages are usually triggered by dead skin cells or dried skin oil, which can clog affected pores and produce the burning and itching that characterize this condition. These symptoms occur after perspiration becomes trapped inside sweat ducts, then gradually seeps into nearby skin and forms stagnating pools that irritate tissues.

Once perspiration is captured beneath the skin, it causes the eruption of small red bumps, known as "papules." These conical bumps appear chiefly on the trunk and extremities, where they often result in a painful, burning sensation — along with intense itching. (A related condition, miliaria crystallina, occurs when sweat collects in the outermost layer of skin — the epidermis — in tiny, transparent blisters. This is more commonly seen in infants.)

Prickly heat occurs most often in hot, tropical climates, and it attacks infants more frequently than any other age group. Typically, the areas of inflammation will develop in skin folds and areas where clothing brushes frequently against the body. Babies and young children frequently develop the rash at the nape of the neck.

Once the condition sets in, it lasts four to six weeks and is marked by the unpleasant "prickling" sensation that usually accompanies the burning and itching. (Healing takes at least a month in most cases because the body requires that much time to grow new sweat duct cells, in order to eliminate those that are plugged up.) Although prickly heat usually occurs in the warm summer months, it can also take place in winter — especially in situations where clothing is worn tightly and without adequate ventilation. Prickly heat is a harmless condition. Although it can occasionally lead to more significant infections, the disorder will eventually clear up by itself in most cases.

What to Do

Adult: To prevent prickly heat, reduce the sweating that triggers this condition by wearing lighter clothing with plenty of ventilation. Wear cotton-based garments whenever possible, and avoid skin-irritating synthetic fabrics. Take cooling baths or showers as frequently as possible.

See your doctor if the red, itchy rash lasts for more than two weeks without beginning to fade, or if the intense "prickling" sensation continues for more than a few days without diminishing.

Infant: The most critical factor in preventing prickly heat is controlling the environmental temperature. If possible, keep the temperature around 72 F. In hotter environments, dress the infant lightly in absorbent cotton clothes. 

Self-care Steps for Prickly Heat

Adult:Rub affected areas with a coarse, damp washcloth to help unclog blocked sweat pores. To relieve itching and redness, apply a 1 percent hydrocortisone cream, available over the counter at most pharmacies. Apply calamine lotion to areas of rash in order to help dry up excess skin oil. Try the old-fashioned remedy of applying wet cornstarch to areas affected by prickly heat.

Infant:  Before treating prickly heat in a baby, check with your doctor.