When summer temperatures leave your skin all hot and bothered — as in, itchy and bumpy — you’ve likely got a common case of heat rash on your hands. Or more likely, you’ll have a rash on other body parts — especially the neck, shoulders and chest and in skin folds like armpits, inner elbows and groin, according to the Mayo Clinic.

Heat rash comes in several forms, says Brooklyn-based dermatologist Eliot Y. Ghatan, MD. They’re basically all caused by the same mechanism: an overproduction of perspiration. Sweat glands produce perspiration to help cool the body down. As sweat evaporates into the air, it takes body heat with it. When there’s too much sweat to escape the body easily, it gets trapped and can bring on heat rash.

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The different types of heat rash are:

  • Prickly heat. Common among babies, this usually mild rash occurs when sweat blocks pores and gets trapped under skin, creating tiny dots or pimples sometimes called “sweat bubbles.” Prickly heat is also known as miliaria.
  • Miliaria crystalline affects the sweat ducts in the top layer of skin, causing fluid-filled blisters that break open easily.
  • Miliaria rubra creates red bumps that can be itchy or feel “prickly.”
  • Miliaria pustulosa is a heat rash that becomes inflamed and pus-filled, signaling infection.
  • Miliaria profunda develops when sweat is buried in a deep layer of skin (the dermis), causing flesh-colored goose bumps. Here’s where heat rash can take a turn for the worst: If skin gets so hot that sweat becomes trapped in the dermis, there’s also a high risk of heat exhaustion or heat stroke. This type of rash should serve as a warning to cool off immediately, says Dr. Ghatan. One other clue: You’re very hot but you’re not sweating.

To prevent and treat heat rash, Ghatan offers these tips.

1. Beat the heat. When you’re really sweating, sit in front of a fan or in an air-conditioned room or take a cool shower. Cool compresses also can help — the idea is to lower body temperature. With just these simple measures, mild cases of heat rash will clear up quickly.

2. Dress cool. Wear lightweight clothing that fits loosely. Garments that are tight against skin won’t allow sweat to evaporate easily. Thin cotton is a good choice.

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3. Skip the run in the sun. Exercising in heat and humidity may make you more susceptible to heat rash. Save outdoor exercise for early morning or early evening when the sun isn’t high in the sky and the air is cooler.

4. Avoid thick or oily skin creams and ointments. Sunscreen is a must year-round, of course, but on hot days choose lightweight lotions or sprays, advises Ghatan.

5. Ditch the itch. If you get a heat rash, dab calamine lotion on it. It won’t make the rash go away faster but it will relieve the itching.

6. Keep an eye out for infection. See your doctor if your rash is pus-filled or inflamed. Moderate to severe heat rash may require treatment with an antibiotic cream or steroid ointment, says Ghatan.

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Denise Foley is a veteran health writer and a former contributing executive editor at Prevention magazine.