Heat rash is a skin condition that occurs when sweat ducts are clogged during hot or humid weather. Most commonly, heat rash looks like small red or pink bumps, which may appear similar to bug bites or pimples. To get rid of heat rash, you should avoid sun, wear breathable fabrics, and put a damp cloth on the skin and let it dry — do not use any lotion or ointment on the skin. This article was medically reviewed by Jason R. McKnight, MD, MS, a family medicine physician and clinical assistant professor at Texas A&M College of Medicine. This story is part of Insider’s guide to Heat Illness.
After a hot day in the sun, have you ever found water bubbles or red bumps on your skin? If so, you’ve likely had a heat rash. Heat rash is a fairly common ailment, especially for the elderly and infants. You can usually get rid of it within hours or days, and it rarely requires a visit to the doctor. Here’s how to recognize the symptoms of heat rash and treat it effectively at home. What is heat rash? Heat rash, also called prickly heat or miliaria, occurs when sweat gets trapped and can’t leave your skin, typically during periods of hot or humid weather.
In most cases, heat rash is caused by clogged sweat ducts, which trap your sweat and cause irritation. You’re most likely to find heat rash in places where you experience excessive sweating and skin-on-skin friction — like the neck, armpits, buttocks, or waistline. That’s because it can be difficult for your body to release moisture in these high-sweat areas, especially if the area is blocked by tight clothing or skin folds. According to a 2008 article in the American Academy of Family Physicians about newborn skin, infants are especially prone to heat rash because their sweat ducts are small and their bodies are not yet adept at temperature regulation. Elderly people are also at a higher risk of heat rash, because the supportive skin tissue that keeps the sweat ducts open tends to break down or collapse as we age.
Overall, heat rash is considered a benign condition by doctors, and associated symptoms of heat illness — like dehydration, heat cramps, or heat exhaustion — are a much bigger concern. What does heat rash look like?
The most common type of heat rash is miliaria rubra, pictured here.
Heat rash commonly appears as red or pink bumps, and may look similar to pimples or bug bites. Sometimes, heat rash can present as skin-colored water bubbles that break easily, or slightly larger, painful cysts. This chart can help you identify the three different types of heat rash:
How to get rid of heat rashMost cases of heat rash will resolve on their own. To soothe your irritation and get rid of heat rash quickly, here’s how you can treat it at home:
1. If you’re exposed to the sun, go inside First, you’ll want to lower your body temperature to stop the sweating that causes clogged ducts and leads to heat rash. If you’re outside, try to find a place in the shade. Or, if you can, go indoors where there’s air conditioning.2. Put a cool, damp cloth over the area — and then let it dryTo bring down your body temperature and provide temporary relief, wet a small cloth with cold water and place it on the inflamed area for 20 minutes.Then, dry the inflamed area and let it sit, exposed to cool air. If the inflamed area is in a place prone to sweat, like the armpits, you can use baby powder to soothe your skin and prevent further irritation.
3. Avoid lotions, ointments, or any other topical solutions “These clog the skin,” says Dawn Davis, MD, the director of pediatric dermatology at Mayo Clinic Rochester. It may feel automatic to reach for lotion to soothe your rash, but according to Davis, the best thing to do is to let your skin breathe without additives. 4. Avoid scrubbing the areaExfoliation may cause temporary relief, but it can actually incite long-term skin damage, Davis says — especially for children and the elderly, who have more sensitive skin. 5. Change into breathable clothingHeavy or non-breathable clothing, like cotton, also traps your sweat. Consider wearing clothing made of polyester blends instead, which are highly breathable.
If you’re taking care of an infant, be sure the baby isn’t over-swaddled, or wrapped in too many layers of clothing.This can be a problem for people in professions like firefighting and those in the military, too, especially if they travel frequently to warm places.In a 2018 study on occupational heat rash for the Journal of Medical Case Reports, researchers found that wearing flame-resistant clothing in hot working environments led to heat rash; they recommend that workers in these environments change clothes often and make concerted efforts to stay cool and dry. 6. Know how to prevent future cases of heat rashAccording to Davis, the best method of treatment is to understand what causes heat rash, and learn how to avoid it going forward.
“You can prevent and decrease the likelihood of irritation by dressing for the climate, changing positions, and not over-swaddling young kids or elderly people,” Davis says. Davis also recommends taking care of your skin tissue by avoiding the sun, not smoking, and wearing sunscreen. This keeps the skin structure strong, which can prevent the collapsed ducts that lead to high heat rash risk.How long does heat rash last?For adults, heat rash usually resolves within a few hours, or in more severe cases, up to a few days or weeks. There are a few possible timelines for recovery, depending on the severity of your rash:
1. If your heat rash appears as water bubbles on the skin, you’re likely to see a resolution within a few hours, but it may take as long as a few days. 2. If your heat rash presents as redness (and looks like a bug bite or pimples), it may take a couple of days to a few weeks to resolve because the inflammation is deeper, Davis says. 3. If you’re experiencing deep, painful nodules (which is rare), you should check in with your doctor. You may need to take anti-inflammatory medication, like Tylenol, to address the pain; these cases can take longer to resolve, often up to several weeks.While you wait for your rash to subside, you may experience heat intolerance, or discomfort when you’re exposed to warm temperatures. You should also drink plenty of water to prevent dehydration during this time, according to the UK’s National Health Service.
When to see a doctor You should see a medical professional if you’ve been treating your heat rash and it hasn’t improved after several weeks, or if you experience the following symptoms, which could indicate infection: Pus or swollen lymph nodesA fever or chillsExcessive pain increased swelling around the rash Most infants grow out of heat rash when their parents learn to dress them in more breathable clothing, according to Davis, or when they reach toddlerhood and their sweat ducts mature.If your child frequently has heat rash, you should talk with your doctor further about preventive measures and how to keep them cool.