Many different types of skin rashes exist. They can be concerning, uncomfortable, or downright painful. One of the most common types of rash is heat rash, or miliaria.
Heat rash is a skin condition that often affects children and adults in hot, humid weather conditions. You can develop heat rash when your pores become blocked and sweat can’t escape.
The cause of heat rash is often friction on the surface of the skin. Adults usually develop heat rash in the parts of their bodies that rub together, such as between the inner thighs or under the arms. Babies often develop heat rash on their necks, but it can also develop in skin folds such as the armpits, elbows, and thighs.
What it looks like
Different types of heat rash can range in severity, and they all look a little different.
Miliaria crystallina is the most common and mildest form of heat rash. If you have miliaria crystallina, you’ll notice small clear or white bumps filled with fluid on the surface of your skin. These bumps are bubbles of sweat. The bumps often burst.
Contrary to popular belief, this type of heat rash doesn’t itch and shouldn’t be painful. Miliaria crystallina is more common in young babies than in adults.
Miliaria rubra, or prickly heat, is more common in adults than in children and babies. Miliaria rubra is known to cause more discomfort than miliaria crystalline because it occurs deeper in the outer layer of the skin, or the epidermis.
Miliaria rubra occurs in hot or humid conditions and may cause:
- itchy or prickly sensations
- red bumps on the skin
- a lack of sweat in the affected area
- inflammation and soreness of the skin because the body can’t release sweat through the skin’s surface
Bumps that appear due to miliaria rubra can sometimes progress and fill with pus. When this happens, doctors refer to the condition as miliaria pustulosa.
Miliaria profunda is the least common form of heat rash. It can become recur often and become chronic. This form of heat rash occurs in the dermis, which is the deeper layer of skin. Miliaria profunda typically occurs in adults after a period of physical activity that produces sweat.
If you have miliaria profunda, you’ll notice larger, tough, flesh-colored bumps.
Because heat rash prevents sweat from leaving your skin, it may lead to nausea and dizziness.
Heat rash occurs when pores become clogged and can’t expel sweat. This is more likely to happen in warmer months, in warmer climates, and after intense exercise. Wearing certain clothing can trap sweat leading to heat rash and using thick lotions and creams can also lead to heat rash.
It’s possible to get heat rash in cooler temperatures if you wear clothes or sleep under covers that lead to overheating. Babies are more likely to develop heat rash because their pores are underdeveloped.
Call your doctor
Heat rash is rarely serious. Often, it goes away without treatment in a few days. However, you should call your doctor if you begin to experience:
- a fever
- increased pain
- pus draining from the bumps
Call your child’s doctor if your child has heat rash and it doesn’t go away in a few days. Your doctor may recommend that you apply lotions such as calamine or lanolin to relieve itching and prevent further damage. Keep their skin cool and dry to help relieve heat rash.
Find a Doctor
Follow these tips to prevent heat rash:
- Avoid wearing tight clothing that doesn’t allow your skin to breathe. Moisture-wicking fabrics help prevent sweat buildup on the skin.
- Don’t use thick lotions or creams that can clog your pores.
- Try not to become overheated, especially in warmer months. Seek out air-conditioning.
- Use a soap that won’t dry your skin and doesn’t have fragrances or dyes.
Heat rash is a minor discomfort that will resolve itself in a matter of days for most people. Talk with your doctor if you believe you may have something more serious or if you have heat rash that frequently recurs.