Do you have red bumps and prickliness on your skin? You could be experiencing a common type of skin rash: heat rash. Heat rashes can happen in both adults and children, whenever hot and humid conditions occur. They can be annoying, itchy, and downright painful.
In other words, heat rashes are no fun. But what causes them, and how can we avoid them? Fortunately, these skin issues are generally low-key and temporary — and we’re here to tell you all you need to know.
What is a heat rash, exactly?
One of the functions of our skin is to provide temperature control for our body. When you’re hot, you sweat. All over your body, perspiration is manufactured in your sweat glands, and this liquid removes your body heat — a tiny bit at a time — through your sweat ducts and pores.
When those ducts become clogged, sweat can’t get to the surface of your skin. And when it gets trapped inside the top layer of your skin, called the epidermis, it causes a mild inflammation.
Depending on where in your skin the clog happens, the resulting heat rash will show up differently.
Below are the 3 main types of heat rash.
Miliaria Crystallina Heat Rash
This type of heat rash creates blisters that aren’t painful and look like small beads of sweat. Miliaria crystallina happens when sweat becomes blocked right at the top of the skin, where the sweat duct meets the skin’s surface.
Miliaria Rubra Heat Rash
This is the official name for the classic heat rash (sometimes referred to as “prickly heat”) and this version of the rash happens when inflammation occurs deeper down in the epidermis. If you suffer from prickly heat you’ll see small, angry red bumps along with pustules and even blisters, and the rash will feel very irritating and itchy.
Miliaria Profunda Heat Rash
This is the rarest, but also most dangerous, type of heat rash because there are no symptoms (yep, you read that right) so it puts you at risk of heat exhaustion, heat cramps, and heat stroke. It affects the lower dermis layer of the skin and consists of large, firm, light-colored bumps.
Okay, but why am I getting a heat rash?
Your sweat ducts can get clogged in a number of ways, but heat rashes generally happen when air doesn’t circulate properly, which means your sweat won’t evaporate.
Excessive sweating can be the culprit – there’s just too much for the duct to handle. Creases in skin that touch other parts of your skin (neck, armpit, groin) can block sweat. Tight, non-breathable clothing can trap sweat inside. Sweat can get trapped when you’re bundled up in bed with a warm blanket, or when you’re in hot and humid climates. You can also experience heat rash after intense exercise.
The result of any of these instances: your body overheats, and a heat rash appears.
Babies are more likely to get heat rash because their pores are underdeveloped, so it’s easier for the sweat to be trapped. Experts don’t yet know why some adults are more prone to it than others, but some medications can cause heat rash as a side effect.
When should I see a doctor for heat rash?
You don’t need a doctor to diagnose the heat rash, if you can see the reddened skin and bumps and can associate it with conditions of higher temperature. Once your body cools, your heat rash should fade. Over-the-counter remedies, such as lanolin, calamine lotion and hydrocortisone creams, may help.
But your heat rash may be painful, cause swelling and redness that don’t resolve once you’ve cooled down, or result in fever, chills, and pus. If you’re prone to heat rash, it’s important to also be aware of the signs of heat stroke, including high body temperature, confusion, nausea, vomiting, flushed skin, rapid breathing, and high heart rate.
Also, heat rashes may become chronic. If your rashes recur, or if symptoms last more than a few days, a visit to the dermatologist or other skin care professional may help you diagnose and solve additional problems.
Prevention is your best defense!
With heat rashes, prevention is key! It’s important to literally stay cool.
Wear loose clothing. Get into an air-conditioned place, or stand in front of a fan. Don’t exercise when it’s sweltering out. Be smart about your safety in hot and humid weather, and make sure your body is exposed to moving air currents. Drink water. If you’re prone to heat rash, avoid pore-clogging products. Wash your skin frequently to prevent blocked sweat glands. Losing weight can also reduce your risk, as it prevents skin-on-skin contact.
Just remember, most cases of heat rash are mild, and go away within a few days. And with some care, you can stop heat rash from happening in the first place!