It’s a hot summer day. You’re working outside when you start feeling a tingly, prickly sensation on the inside of your elbow. Little red bumps begin to appear. They swell a bit and start itching. Later that day, you notice them on your neck and armpits. You’ve just joined the more than 30 percent of adults around the world who suffer from heat rash as a result of living and working in hot and humid climates. While it’s one of the milder heat-related illnesses—and one you can usually treat yourself—incidences of heat rash are expected to rise with the increase in global temperatures. So it’s good to become familiar with the symptoms and treatment.
Heat rash, known medically as miliaria, occurs when sweat ducts become blocked, trapping sweat beneath the skin. The rash is most likely to form in areas of the body where sweat accumulates, including the neck, chest, back, armpits, groin, elbows, and under the breasts.
Four types of heat rash
The most common form of heat rash is miliaria rubra, also known as “prickly heat.” It’s a mild rash with small, red, inflamed bumps that can either itch or cause a prickling sensation. Miliaria crystallina is also mild. You can recognize it by its small, clear, fluid-filled blisters that look like beads of sweat but don’t itch and aren’t painful.
If those bumps start filling with pus and turn yellow or white, you probably have miliaria pustulosa, which is essentially miliaria rubra that’s become infected.
The least common—but potentially the most dangerous—form of heat rash is miliaria profunda. Its bumps are usually bigger and firmer than the milder forms of heat rash. By blocking the sweat glands deeper in the skin, this form of heat rash makes it harder to regulate your body temperature through sweating. In severe cases, that can lead to heat exhaustion, which can escalate to heat stroke—a medical emergency.
Who gets heat rash?
The simple answer: anybody whose sweat ducts become blocked as a result of heat and humidity. But these groups of people are more susceptible than others:
- Babies and young children, whose sweat ducts aren’t fully developed and can become easily blocked
- Newborns, mostly as a result of parents overdressing them
- People living in hot, humid climates
- People who sweat a lot due to physical activity, fever, or medical conditions
- Those who are overweight or obese—the more overweight you are, the more likely you are to have skin folds where sweat can get trapped
- People who wear tight, non-breathable clothing, which can block sweating
- People on certain medications, including clonidine, beta-blockers, and opioids, which can increase sweating
- The elderly, because your sweat glands work less efficiently as you age
What you should do if you get it
The milder forms of heat rash usually clear up by themselves in one to three days. Moderate cases may take up to a week. If you think you might have a more serious case—for example, if the rash shows signs of infection or you have fever and chills—it’s best to consult a healthcare professional for proper diagnosis and treatment.
Here are some ways to treat heat rash symptoms:
- Use cold compresses. Cool, damp cloths applied to affected areas help relieve itching and inflammation
- Wear loose, breathable clothing, such as cotton
- Stay cool. Air conditioning will help ease symptoms
- Use over-the-counter treatments, such as calamine lotion, aloe vera, or a mild 1% hydrocortisone cream to reduce itching
- Don’t scratch. It only makes the itching worse and increases the risk of infection
Steps you can take to prevent it in the first place
Since heat rash occurs when sweat glands are blocked due to trapped sweat, it makes sense that anything that reduces sweating will help prevent it. Dermatologists and healthcare providers recommend keeping your skin dry and cool to significantly lower your chances of developing heat rash.
Avoid using heavy creams and ointments, which can block pores and trap sweat. Some experts suggest using barrier creams with zinc oxide, but only if applied thinly and carefully.
Stay hydrated, as proper hydration helps the body regulate temperature more efficiently.
Make sure to keep your skin clean, wash gently, and avoid harsh soaps that can cause irritation.
It’s also a good idea to shower frequently after sweating and change out of sweaty clothes quickly to prevent blocked pores.
Wear loose-fitting clothes that don’t rub against your skin. Lightweight fabrics like cotton allow air to circulate and wick away moisture. Try to avoid synthetic fabrics whenever possible—they don’t breathe well and tend to trap heat and sweat.
Staying on top of heat rash is no sweat
With global temperatures rising, it’s more important than ever to know the symptoms of heat rash and how to get rid of it quickly and safely. Heat rash can often be mistaken for hives or insect bites. Learning to tell the difference between mild forms you can treat at home and more serious cases that require a healthcare provider is a simple way to keep your skin—the largest organ in your body—healthy and working properly.
