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Here’s How to Get Rid of Heat Rash, According to Dermatologists

Plus what those pesky bumps are, exactly.
illustration of heat rash of dark skin
Wondering how to get rid of heat rash? Cooling off is essential.Getty Images

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:

  • Small red, white, or grayish—depending on your skin tone—bumps that are uniform (meaning the bumps all look the same) and resemble small pimples or blisters. These bumps often occur in areas where there’s pressure and friction from clothing along with sweating, such as the neck, skin folds and creases, chest, groin, back of legs, or butt.
  • On darker skin tones, redness may not be as visible, Dr. Aigen says, but you can still see—and feel—the bumps. “If you close your eyes, you can feel a bumpy rash,” she says.
  • The rash is itchy and uncomfortable. “Many people say it feels like a prickly sensation on the skin,” Dr. Aigen says. Some people also say the rash burns, Dr. Shah adds.

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How to get rid of heat rash quickly

The good news is that heat rash is totally benign, meaning that it’s not going to harm you, Dr. Aigen says. Symptoms of heat rash also go away on their own.1 By cooling off the skin (which stops the sweating), changing your clothing, and/or taking gentle skin-care steps, you can likely relieve heat-related bumps fairly fast.

Your symptoms should resolve or be getting much better within a day or so, Dr. Shah adds. Here’s what you can do to get rid of heat rash:

Make a beeline out of the heat. Get indoors where there’s a fan or air conditioning. In fact, just go stand directly in front of the fan or A.C. blower (if you can). The quicker you can cool down your skin, the better, Dr. Shah says.

Take off tight clothes. If possible, remove snug clothing items as soon as you can, Dr. Sherber suggests. Stripping off close-fitting clothing eliminates friction and allows your skin to breathe so that sweat no longer gets trapped in your sweat ducts.

Get into a cool shower or bath. Cool water calms your skin and is very helpful for getting rid of heat rash quickly, Dr. Sherber says. “Even a cool compress placed on the skin or misting the skin with cool water can be beneficial,” she says.

Consider a topical treatment. If your skin is especially itchy and irritated, a mild topical steroid, such as a 1% hydrocortisone cream, which you can purchase over the counter at a drugstore, can soothe the affected area and reduce inflammation, Dr. Aigen says. (You may think to reach for calamine lotion, but she warns that some people are sensitive to this topical anti-itch medication, which can paradoxically worsen irritation. She recommends avoiding calamine for this reason.)

Go for oats. If you feel extra itchy, you can also try soaking in a cool bath with colloidal oatmeal, Dr. Aigen recommends. Colloidal oats (which are made from ground oats) have been found to decrease inflammation and itchiness in the skin, according to research in the Journal of Drugs in Dermatology.2

Keep your hands off. Touching your skin is no good if you have a heat rash. We know: Rubbing and scratching can bring such temporary relief. But it can cause further irritation and you can also break your skin with your nails, increasing the risk of a secondary skin infection, Dr. Aigen warns.

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How to prevent heat rash in the first place

If you live in a hot, humid climate or often work out outdoors in the heat, then you may be more at risk for getting heat rash, according to Cleveland Clinic. Still, the tips below can help anyone stay as cool as possible and prevent heat rash when life gets sweaty:

Dress for the weather. Your black leggings and tank might make you look badass when tackling a Saturday long run, but tight fabrics in dark colors (which absorb more heat) are a recipe for overheating skin and trapping sweat, Dr. Sherber says. Instead, opt for loose-fitting, lighter-colored clothing in breathable fabrics for working out—or hanging out—on hot days.

Head indoors. If it’s going to be a scorcher of a day and you know you’re prone to heat rash, lift weights or run on the treadmill indoors in the comfort of the A.C. that day, if you can, Dr. Aigen suggests. Similarly, if you feel as if you’re overheating, it’s a good idea to pop in somewhere with A.C. until you cool down. (That can also help prevent heat exhaustion and heat stroke.)

Bring fans. Going somewhere like an outdoor music festival or spending the day at a barbecue in the park? Be prepared with portable fans, which you can use to help keep skin cool, or misters that spray water on your skin, Dr. Shah suggests.

Switch your moisturizing products. Ointments and body oils may have been key for hydrating your skin through cooler days, but as the temperature heats up, you’ll want to switch to a lighter lotion, Dr. Sherber says. “Thicker formulas tend to be occlusive (they create a barrier that prevents moisture loss) and can exacerbate blockage of the sweat glands,” she explains. Look for the word “lotion” on the label (rather than “ointment” or “cream”) and steer clear of petrolatum (petroleum jelly), an ingredient that’s great for locking in moisture in the winter, but is too heavy when you’re dealing with heat rash.

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What if heat rash doesn’t go away?

It’s comforting to know that the pesky bumps from heat rash will disappear on their own—again, typically within a couple of days—but what if that’s not happening for you? “If the rash is persistent, if the bumps begin to ooze, or if the rash is accompanied by fever or nausea, consult a dermatologist,” Dr. Sherber says. There’s a possibility that your skin condition isn’t a heat rash at all. (For instance, if fluid-filled bumps hurt and affect only one side of your body, she notes that this could be shingles, an infection from the varicella-zoster virus that causes a painful rash.)

If you’re dealing with heat rash, the good news is that there are better days ahead (probably tomorrow). Just breathe—and help your skin do the same.

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  1. StatPearls, Miliaria
  2. Journal of Drugs in Dermatology, Anti-inflammatory Activities of Colloidal Oatmeal (Avena Sativa) Contribute to the Effectiveness of Oats in Treatment of Itch Associated With Dry, Irritated Skin