Beauty Health

Here’s What a Heat Rash Actually Looks and Feels Like

If you’re wondering how to get rid of heat rash—in all its itchy, prickly, sting-y glory—we feel for you. The irritating condition is one of the major downsides of warmer weather (add it to the long list of annoying summer skin problems—lookin’ at you, mosquito bites and sunburn).

If you’re a parent, you may be more in tune with heat rash, as it’s often seen in young kids. “While heat rash can happen at any age, it’s more commonly seen in babies and toddlers than in adults, since their sweat glands are not yet mature,” Noëlle Sherber, MD, board-certified dermatologist and clinical associate professor of dermatology at George Washington University School of Medicine and Health Sciences, tells SELF.

Still, heat rash happens to adults too. Here, experts explain what it is, what it looks like, and, most importantly, how to get rid of heat rash and prevent it from cropping up to begin with.

What is heat rash? | What does a heat rash look like? | How to get rid of heat rash | How to prevent heat rash | What if heat rash doesn’t go away?

What is heat rash?

When you step out into the heat—especially if the humidity is up—the 2 to 4 million sweat glands all over your body trigger the secretion of a fluid that evaporates from your skin and cools you down, according to the International Hyperhidrosis Society. Most of your sweat ducts are eccrine glands that pump out a clear and odorless fluid. (Your apocrine sweat glands, on the other hand—mostly found in the skin of the armpits and groin—produce a fluid that, well, stinks.)

Sometimes this sweating process can go sideways, leading to heat rash. “Heat rash typically occurs when you’re in a hot and humid environment and sweat glands become obstructed,” Sonal Shah, MD, board-certified dermatologist and clinical associate professor in the department of dermatology at Case Western Reserve University, tells SELF. “Normally, when sweat is excreted, it goes onto the surface of your skin, but when blocked, it can leak out underneath the skin where it becomes trapped, causing inflammation,” she explains.

Once sweat is trapped under the surface of your skin, heat rash may begin to appear. Heat rash is also called prickly heat and miliaria, but it can also be dubbed a “sweat rash” colloquially. No matter what you call it, the rash can occur in response to any hot environment. However, exercising in the heat is the perfect storm for excessive sweating that can cause heat rash, Dr. Shah says. “When you’re doing a lot of physical activity, you’re really working those sweat glands,” she says. “Plus, sports bras or athletic leggings are not typically made of the most breathable fabrics.”

Heat rash often happens when you’re outside in hot weather, but it can affect you when you’re indoors too. As long as you’re sweating and something (like tight-fitting clothing or being wrapped up in blankets in bed) is blocking that sweat from properly releasing onto the surface of your skin and evaporating, heat rash can occur. “Hot and humid weather is a risk for heat rash, but don’t forget that it can also happen if you’re sweating at night in your bed,” Alyx Cali Rosen Aigen, MD, a board-certified dermatologist with the University of Miami Health System, tells SELF.

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What does a heat rash look like?

A heat rash has a distinctive appearance, but when trying to determine whether or not you have one, it’s also important to think about the circumstances of the skin rash, Dr. Aigen says. For example, did you spend a lot of time outside on an unusually hot day? Did you go to an outdoor boot camp in the blazing sun? Did you wake up soaked from sweat in bed? You get the picture. This is what to look for with heat rash: