Everything You Need to Know About Heat Rash

A must-read before spending time in the sun.

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Photo by Frida Marquez/Getty Images

This article originally appeared on MIMI

When you think of summer, you probably picture relaxing with friends and family on the beach, looking like a bronze goddess, and fruity drinks. What you try to forget are the annoying downsides, like excessive sweating, sunburns, and heat rash. We're all familiar (too familiar, probably) with sweating and sunburns, but what is heat rash, really?

I decided to find out once and for all. I enlisted the help of Rachel Nazarian, M.D. of Schweiger Dermatology Group to get to the bottom it.

Classic heat rash (doctor talk: miliaria), "is a red, sometimes itchy or painful rash that can occur after skin has been exposed to a hot or humid environment." Also included: small blisters. Yikes.

In other words, heat makes you sweat. We sweat to lower our body temperature. So when the sweat can't escape, the skin gets angry. Cue heat rash forming.

Now, prepare for your mind to be blown in a semi-embarrassing way. Heat rash technically has nothing to do with UV rays from the sun. The only true cause of heat rash is, well, heat. That doesn't mean you should skimp on the SPF, though.

Luckily, there are ways to avoid it. Obviously, spending long periods of time outside is no good, but if that is unavoidable (especially on a long holiday weekend), wear light, breathable clothing, avoid lathering up with thick creams and ointments, and try to keep skin as cool and dry as possible.

If you do begin to feel a rash developing, immediately head inside. Nazarian recommends removing any restrictive clothing items, washing the skin with cold water, and applying a topical hydrocortisone lotion to decrease the inflammation if you have it on hand.