Sweating Can Lead to Heat Rash:
Here’s What To Do About the Prickly Problem
Extreme sweating can leave you feeling damp, embarrassed, slippery, and more. But when humidity levels and temperatures soar, sweating can also lead to an uncomfortable heat rash.
Heat rash (also called prickly heat) can strike when sweat gets trapped under the skin, especially when the weather is hot and humid.
Here’s how to recognize heat rash, treat it, and protect yourself from getting it in the first place.
What Does Heat Rash Look and Feel Like?
If you’ve been sweating even more than usual and notice red, itchy bumps on your skin; small, superficial blisters; or general uncomfortable redness; you may have heat rash (also called miliaria or prickly heat). Other symptoms include mild swelling and a “prickly” or stinging sensation on the skin. This can erupt on the chest, shoulders, neck, thighs, along folds of the skin, or wherever clothing causes friction. Babies and young children are especially prone to heat rash on their faces and necks and in the diaper area. Occasionally, the fluid filled sacs of heat rash can become inflamed and pus-filled, potentially leading to an infection.
What Causes Heat Rash?
Heat rash occurs when sweat becomes trapped under the surface of the skin. Seeping into nearby tissue, the sweat can then lead to tiny pockets of swelling which cause a tell-tale rash and, sometimes, little blisters. Heat rash is more common in babies and young children because their sweat ducts are not yet fully developed and can easily be disrupted. Children are also at greater risk for heat rash because they are slower to adapt to temperature fluctuations.
Among adults, heat rash often shows up while on a trip to a warmer, more humid location (humidity causes increased sweating), with sudden weather changes, or if you’re doing activities that cause you to sweat more than normal (like exercising or working in hotter temperatures). Heat rash can also strike people who have an illness or injury that keeps them in bed or in a chair for extended periods of time with sweat and heat accumulating underneath them, or anyone sleeping with too many blankets or warm PJs on. Tight bandages, medication patches, or constricting clothes can also increase risks of localized heat rash. In terms of excessive sweating sufferers, specifically, Dr. Zakiya Rice of Dermatology Associates of Georgia notes, "It is not uncommon for a patient with primary focal hyperhidrosis to also present with a concomitant dermatitis [skin irritation]" and heat rash, she says, is certainly one of those possible irritations.
How is Heat Rash Treated?
Most heat rash is mild and can be cared for at home with simple cooling tactics. Try to keep cool and limit your body’s need to sweat further so that skin can have time to heal. Wear loose, comfortable, breathable clothing, especially over any areas suffering from heat rash. For inflammation and irritation, you can use a hydrocortisone 1% cream (just don’t use it on your face unless recommended to do so by a healthcare professional). Calamine lotion can also be soothing. Sometimes moisturizing can help, but avoid anything oily that could clog pores; aloe vera is a good choice. Cold compresses and lukewarm showers or baths (without soap) are also useful. Tepid oatmeal baths are another option. Avoid scratching, especially at any bumps. If you must touch the affected skin, pat rather than scratch or use gentle exfoliation in the shower.
How Can Heat Rash Be Prevented?
Limiting overheating and sweating beyond what’s normal for you is the primary means of preventing heat rash. Also important is keeping young children cool and sticking to breathable, loose clothing. Avoid tight-fitting and non-breathable garments that can make sweating worse. We know it’s not always possible to stay cool and dry, especially with hyperhidrosis, but even finding ways to give skin a sweat-break for several hours per day can help.
Other important heat rash prevention tips include:
- Using antiperspirants in the underarms as well as in skin folds that can be prone to sweat build-up and heat rash. Be sure that skin is completely dry before applying antiperspirant to help avoid potential skin irritation. Learn more tips for using antiperspirants beyond the underarms here. And don’t worry, although antiperspirants work by creating superficial plugs to block glands from releasing sweat onto the skin, this is different than the sweat-under-the-skin process that causes heat rash. With antiperspirants, when a duct becomes closed-off, there’s a biofeedback mechanism that then causes the associated sweat gland to produce less sweat. With heat rash, on the other hand, sweat seeps out of the sweat duct and into nearby skin tissues, where it doesn’t belong and where it causes irritation.
- Staying well hydrated in warm temperatures, especially if exercising or working outdoors.
- Keeping cool in the summer, a heatwave, or if traveling to a warmer environment. Try taking lukewarm baths or showers; wearing a wide-brimmed, light colored hat; applying cool packs or compresses (especially to the neck, underarms or feet for quick cooling effects); staying indoors or in the shade if possible; keeping sleeping areas cool and using breathable, moisture-wicking bedding; avoiding hot foods, heavy foods, and spicy foods when heat and humidity are high; and keeping a spray bottle handy for periodic self-spritzing.
Typically, heat rash (even in babies and toddlers) will clear up by itself. But if you notice any signs of infection or heat exhaustion, contact a healthcare provider.
Warning signs related to the rash and potential infection include:
- Fever or chills
- Rash that doesn’t go away after a few days of self-care and cooling
- Increased pain, swelling, redness, or warmth around the affected area
- Pus draining from the rash
- Swollen lymph nodes in the armpit, neck or groin.
Warning signs of heat exhaustion include:
- Cool, moist skin with goosebumps (even in the heat)
- Heavy, unusual sweating
- Rapid heartbeat
- Low blood pressure or lightheadedness when going from sitting to standing
- Muscle cramps
If you or someone else seems to be experiencing heat exhaustion, the Mayo Clinic recommends:
- Stopping all activity and resting
- Moving to a cooler place
- Drinking cool water or sports drinks
Contact a healthcare provider or emergency medical services if signs or symptoms of heat exhaustion don’t improve or worsen. Seek immediate medical attention if the situation progresses to confusion, agitation, loss of consciousness, or if the overheated person is unable to drink.
Heat wave events are becoming more common and we already know that excessive sweating is common (affecting 4.8% of the population). So, we hope this information about heat rash and sweating helps you to stay healthy and comfortable - no matter the temperature.
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