Most heat rash clears up on its own once you cool the skin down, and the best things to use on it are simple: cool compresses, calamine lotion, and lightweight moisturizers that won’t clog your pores. The key is removing the heat and sweat that caused the rash in the first place, then using a few targeted products to ease the itch while your skin heals.
Cool the Skin First
Before reaching for any product, the single most effective step is lowering your skin temperature. Press a cool, damp cloth against the rash, take a cool shower, or move into an air-conditioned room. Once the skin cools, mild heat rash tends to clear quickly on its own. Let your skin air-dry rather than rubbing it with a towel, which can irritate the blocked sweat ducts further.
Calamine Lotion for Itching
Calamine lotion is one of the most widely recommended topical treatments for heat rash. It contains zinc oxide and iron oxide, which work together to cool the skin, reduce itching, and dry out any oozing or weeping bumps. Apply a thin layer directly to the rash and let it dry on your skin without rubbing it in.
A few precautions: don’t apply calamine to open wounds or broken skin, and keep it away from your eyes, nose, mouth, and genital areas. If the rash gets worse after applying it or you develop new irritation, stop using it.
Moisturizers That Won’t Make It Worse
Heat rash happens when sweat ducts get blocked, so anything that sits heavily on the skin can slow healing or make the rash worse. Avoid oily or greasy moisturizers, thick sunscreens, and heavy cosmetics on the affected area.
Instead, use a moisturizer containing anhydrous lanolin (sometimes labeled as “wool fat”). This ingredient actually helps prevent sweat ducts from getting clogged rather than sealing them shut. In people with recurring heat rash, applying anhydrous lanolin before exercise has been shown to help prevent new bumps from forming. For severe or deep heat rash, topical lanolin has produced dramatic improvement in clinical settings.
Colloidal Oatmeal Baths
If the rash covers a large area or the itching is widespread, a colloidal oatmeal bath can provide relief. Oats contain natural compounds called avenanthramides that reduce inflammation and itching. The starches and other components in oatmeal also form a thin protective coating on the skin that helps lock in moisture and block irritants.
To prepare one, add about half a cup to one cup of colloidal oatmeal to a bathtub of lukewarm water (not hot, which would aggravate the rash). Mix the oatmeal in while the tub is filling so the water pressure disperses it evenly. The water should look milky. Soak for 10 to 15 minutes. You can buy colloidal oatmeal packets at most drugstores, or make your own by grinding plain oats in a blender until they’re fine enough to dissolve in water rather than sinking to the bottom.
What to Wear While It Heals
The clothing you wear matters as much as what you put on the rash. Tight fabrics trap sweat against the skin and keep those blocked ducts from clearing. Choose loose-fitting garments that allow airflow, and look for moisture-wicking fabrics that pull sweat away from the skin and spread it across a larger surface area so it evaporates faster. Features like venting and gussets improve airflow even more.
Cotton and other breathable natural fibers are a solid choice. The National Institute for Occupational Safety and Health has long recommended breathable fabrics like cotton and wool for people working in heat. Lightweight, moisture-wicking synthetics designed for athletic wear also work well, as long as they fit loosely.
What Not to Use
Some common products can actually make heat rash worse by further blocking sweat ducts. Avoid these on the affected area:
- Heavy ointments or petroleum-based products that create an occlusive barrier over the skin
- Greasy sunscreens or oil-based cosmetics
- Scented lotions or perfumed body products that can irritate already-inflamed skin
- Hydrocortisone cream unless specifically recommended by a provider, as overuse on heat rash can thin the skin in areas prone to friction
Signs the Rash Needs More Than Home Treatment
Heat rash can occasionally lead to a bacterial infection, especially if you’ve been scratching and bacteria enter through broken skin. Watch for skin around the rash that becomes swollen or feels warm to the touch, pus or increasing redness spreading outward, or symptoms like fever, nausea, or chills. These signs point to a secondary infection, most commonly caused by staph bacteria, that may need antiseptic treatment or antibiotics.
A rash that persists for more than a few days after you’ve cooled down and kept the skin dry is also worth having evaluated. Most heat rash resolves fairly quickly once the triggers are removed, so a rash that lingers could be something else entirely, like a fungal infection or contact dermatitis, which would need a different approach.