Baylor College of Medicine

"The sun is the No. 1 culprit in skin cancer," said Dr. Ida Orengo, professor of dermatology at Baylor College of Medicine.

Don’t sweat the heat rash

Kaylee Dusang


Houston, TX -
Media Component
Rajani Katta, M.D.

The summer heat can bring a multitude of concerns, including uncomfortable heat rashes. A Baylor College of Medicine dermatology expert offers insight on what causes these rashes and advice on prevention and treatment. Most importantly, look to heat rash as the first indicator of a more serious issue.

“When heat rash develops, your skin is giving you a warning that if this continues, you could really have some severe symptoms, from heat exhaustion to heat stroke,” said Dr. Rajani Katta, dermatologist and clinical assistant professor at Baylor. “It is essential to remove yourself from the heat first since a heat rash is an early sign of becoming overheated.”

Heat rashes are different than sunburns, she explains. A heat rash occurs when sweat ducts become blocked and the sweat cannot evaporate from the skin. Sunburns occur when the skin becomes damaged from the sun’s ultraviolet rays.

“With sunburn, the skin is usually red, it might feel hot and blister, but all of that is due to damage to the skin – and that can be dangerous over the long term,” she said. “A heat rash occurs simply because the sweat ducts become blocked. It does not indicate that there is any damage to the skin, and it does not increase your risk of skin cancer. It’s uncomfortable, but in most cases it’s not dangerous.”

Heat rashes tend to occur in hot, humid climates. Individuals most at risk for heat rashes include infants, those who often exercise outside in the heat and those who are overweight or with extra skin folds that can trap sweat. A heat rash also could happen if clothing is too tight, hindering sweat from evaporating.

Katta said there are two common versions of a heat rash – one with small blisters that resemble beads of sweat and another that forms deeper within the skin and looks similar to acne.

“That deeper type of rash is sometimes called ‘prickly heat’ because it can be really irritating,” she said. “It can be prickly, itchy and uncomfortable.”

The best way to avoid a heat rash is being cognizant about how you spend your time in the heat. Katta recommends wearing looser clothing versus tight, so that the air can circulate and keep you from becoming overheated. She adds that it is a good idea to not spend too long outdoors if the temperature is high, and opting for indoor activities to stay cool.

“In Houston especially, this is something that could be concerning,” she said. “If you are exercising intensely you need to make sure you are not getting overheated. If you are a runner, you don’t want to be running in the middle of the day. You really want to be sticking to those cooler times of day or perhaps stay indoors. The other part of that is the clothing that you are wearing. You really want to think about wearing the kind of fabrics that allow sweat to evaporate.”

To treat a heat rash, the first thing Katta recommends is to get out of the heat and find a cool place to rest. Although a heat rash tends to go away by itself, applying a cool compress can help soothe the irritation.

If the rash is not disappearing on its own after a few days or if it is becoming more severe, Katta recommends visiting a doctor. The doctor will typically prescribe medication to help with the inflammation.

“In general, for treatment, we just really recommend getting out of the heat,” she said. “Generally, it will go away on its own. The most effective treatment is to take away the triggering factors.”

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