Heat rash in adults usually clears up within a few days once you cool your skin and stop the sweating that caused it. The single most effective treatment is getting out of the heat, but there are several things you can do to speed healing and relieve the itch while your skin recovers.
What Heat Rash Actually Is
Heat rash happens when sweat gets trapped beneath your skin because the ducts leading from your sweat glands to the surface become blocked. The trapped sweat irritates the surrounding tissue, producing bumps, blisters, or itching depending on how deep the blockage occurs. Adults most commonly develop it in skin folds, on the chest, back, or anywhere clothing traps moisture against the body.
There are three types, and knowing which one you have helps you decide how aggressively to treat it:
- Miliaria crystallina: The mildest form. Sweat ducts are blocked right at the skin’s surface, producing tiny 1 to 2 mm clear blisters that look like beads of sweat sitting on your skin. There’s no redness or inflammation, and they pop easily. This type resolves on its own within days.
- Miliaria rubra (prickly heat): The most common type in adults. The blockage sits deeper in the outer skin layer, causing red, 2 to 4 mm bumps on an inflamed background. This is the one that itches intensely and feels prickly.
- Miliaria profunda: The deepest form, where sweat leaks into the middle layer of skin. It produces flesh-colored bumps on the trunk and limbs that, surprisingly, don’t itch. This type is rare but can interfere with your body’s ability to cool itself if it covers a large area.
Cool Your Skin First
Every other treatment is secondary to this step. Move to an air-conditioned space or at least a shaded area with airflow. Take a cool (not cold) shower and let your skin air-dry completely rather than toweling off aggressively. If you can’t get to air conditioning, a fan directed at the affected area helps evaporate the moisture that’s keeping your pores blocked.
Avoid anything that makes you sweat again for the next several hours. That means skipping exercise, staying out of direct sunlight, and keeping physical activity to a minimum until the rash starts to fade. Most people notice improvement within 24 hours of getting cool and staying cool, with the rash clearing fully within a few days.
Relieve the Itch
For miliaria rubra, the itching can be distracting enough that you need more than just cooling down. Calamine lotion is one of the most accessible options. It contains zinc oxide and iron oxide, which soothe irritated skin and help dry up any oozing or weeping from the rash. Apply a thin layer directly to the bumps and let it dry. You can reapply as needed throughout the day.
A low-strength hydrocortisone cream (available over the counter at most pharmacies) can reduce inflammation and itch for more stubborn patches. Use it sparingly and for no more than a few days, since prolonged use on irritated skin can thin it further. Avoid thick, greasy creams and ointments on the rash itself, as they can trap more sweat and make the blockage worse. Look for lightweight, water-based formulas when possible.
Cool compresses, a damp cloth held against the skin for 10 to 15 minutes, also provide immediate relief without any product at all.
What to Wear While It Heals
Tight clothing is one of the most common triggers for heat rash in adults, and what you wear during recovery matters as much as any cream you apply. Switch to loose-fitting clothes made from lightweight, breathable fabrics. Cotton works well because it absorbs sweat and allows airflow. Moisture-wicking athletic fabrics can also help, but avoid anything that fits snugly against the affected area.
If the rash is in a skin fold (under the breasts, in the groin, behind the knees), try to keep those areas as dry and separated as possible. A light dusting of plain cornstarch or talc-free body powder can absorb excess moisture, though you should avoid applying powder directly to actively inflamed or broken skin.
Preventing It From Coming Back
Heat rash tends to recur in people who’ve had it before, especially during hot, humid months or when returning to the conditions that triggered it. A few strategies make a real difference:
- Shower promptly after sweating. The longer sweat sits on your skin, the more likely it is to block the ducts.
- Avoid heavy moisturizers in hot weather. Thick creams can seal sweat ducts the same way humidity does.
- Use anhydrous lanolin before exercise. For people with recurring heat rash, applying anhydrous lanolin (a waxy, water-free skin protectant available at most pharmacies) before physical activity has been shown to help prevent new lesions from forming. It works by keeping the sweat duct openings clear.
- Sleep in a cool room. Nighttime sweating in a warm bedroom is an overlooked trigger, especially for rashes on the back and chest.
Signs the Rash Needs Medical Attention
Most heat rash resolves on its own without complications. But if your rash hasn’t improved after a few days of staying cool and keeping the skin dry, something else may be going on. Watch for pus-filled bumps, increasing pain rather than just itch, red streaks spreading from the rash, swollen lymph nodes near the affected area, or fever. These signs suggest a secondary bacterial infection in the blocked sweat ducts, which needs treatment beyond home care.
Miliaria profunda, the deep form that causes flesh-colored bumps without itching, also deserves medical evaluation if it covers a large area. Because it disrupts normal sweating, widespread miliaria profunda can impair your body’s ability to regulate temperature, raising the risk of heat exhaustion during physical activity or continued heat exposure.