Prickly Heat: When Sweating Hurts

Q: When I sweat, it's really painful. It feels like I'm being stabbed into my back and upper chest with needles. There is no rash, only an occasional itch. Sometimes the sweating comes on quickly and out of nowhere, as if it were a hot flash. But I've gone through menopause and I don't get hot flashes any more.

A: Sweating in hot, humid weather or under heavy clothing can result in poor function of the sweat glands. They act as though they are blocked, so sweat does not get to the surface of the skin. Evaporation of sweat is a key way for the body to cool when internal body temperature rises.

This obstruction of sweat can take place in different levels of the skin. If the sweat ducts within the upper level of the skin, called the epidermis, are blocked, it results in miliaria rubra, or "prickly heat." This can cause tiny pink bumps on areas such as the neck, chest, or back. These bumps can be very itchy and painful. Areas of skin that are rubbed by clothing can be especially irritated.

Prickly heat can occur after any event that causes sweating, including hot weather, exercise, stress, or illness. People who move to a warmer climate may have excessive sweating and prickly heat until they adjust to the new climate.

Staying cool is the best way to prevent this problem. If you have a problem with prickly heat, wear loose clothing and stay in an air conditioned environment when possible. Applying non-perfumed, over-the-counter lotions that contain menthol can be soothing to the rash.

If the rash persists, see your doctor to make certain that your symptoms are due to prickly heat and not some other disorder. Your doctor may also prescribe cortisone cream to apply to the rash to reduce redness, itching and pain.

See All Harvard Articles on Skin Care        

More on MSN Health & Fitness:

• Heat Rash
• Heat-Related Illnesses
• Folliculitis

Rebecca Campen, M.D., J.D. is an Assistant Professor of Dermatology at Harvard Medical School and former Deputy Director of the Harvard/Massachusetts General Hospital Cutaneous Biology Research Center (CBRC). She currently serves as Senior Advisor to the CBRC and divides her time between clinical practice of dermatology at the Massachusetts General Hospital and private practice in Savannah, Georgia. Dr. Campen is the author of two books for medical students and residents, Going Into Medical Practice and Blueprints in Dermatology.

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