A heat rash typically looks like tiny bumps on your skin. These bumps are sometimes filled with fluid. They can show up anywhere that you sweat a lot, like under the breasts, the groin, or the face.

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.

Many different types of skin rashes exist. They can be concerning, uncomfortable, or downright painful. Heat rash is one of the most common types.

Different types of heat rash can range in severity, and they all look a little different.

Miliaria crystallina

This 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 that 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 infants than in adults.

Miliaria rubra

This type, or “prickly heat,” is more common in adults than in children and babies. Miliaria rubra is known to cause more discomfort than miliaria crystallina because it occurs deeper in the outer layer of the skin.

Miliaria rubra occurs in hot or humid conditions and may cause:

  • itchy or prickly sensations
  • 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

Miliaria profunda is the least common form of heat rash. It can recur often and become chronic, or long-term. 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 large, tough, flesh-colored bumps.

Because heat rash prevents sweat from leaving your skin, it may lead to nausea and dizziness.

These images show the difference between the three types of heat rash.

Heat rash often causes symptoms in sweat-prone areas, like:

  • the face
  • the neck
  • underneath the breasts
  • beneath your scrotum

The symptoms can involve:

  • small raised spots called papules
  • an itching sensation
  • slight swelling

The spots may appear red on light skin tones. For people with dark skin tones, they might appear as white globules with darker halos around them.

The spots can be more understated and harder to identify on dark skin tones. But a dermatologist or physician will be able to see them using a dermoscopy, where they use a small, lighted microscope to zoom in on the skin.

Heat rash occurs when pores become clogged and can’t expel sweat. This is more likely to happen in warmer months or climates, or after intense exercise.

It can also occur due to:

  • wearing clothing that can trap sweat
  • using thick lotions or creams
  • experiencing friction on the surface of skin

Adults usually develop heat rash on the parts of their bodies that rub together, like between the inner thighs or under the arms. Babies often develop heat rash on their necks, but it can also develop in skin folds like those of the armpits, elbows, and thighs.

Heat rash usually resolves without treatment in a few days. If the discomfort becomes too severe, you can try methods at home that help soothe itching and reduce skin temperature.

Some medicines/creams you can buy to manage heat rash include:

  • Over-the-counter (OTC) hydrocortisone cream applied one to two times a day can help soothe itching.
  • OTC antihistamines can also take an effect against itching.

Home remedies for heat rash

Aside from OTC medications and creams, there are a number of herbal or non-medicinal remedies that might soothe the redness and itching. These include:

  • Apply a cold compress. Using an ice pack or chilled cloth can help you bring down redness, swelling, and itching. If using an ice pack, be sure to wrap it in a towel or old t-shirt — you don’t want to experience freezer burn.
  • Take a low-temperature bath. A cold or lukewarm shower can also help you reduce the temperature of your skin and soothes itching. It might help to try an exfoliant to help open the affected pores.
  • Keep indoor temperatures cool. Use a fan or air conditioning to cool down your room. If you’re on bed rest, it’s important to move around to let air circulate your body.
  • Stick with loose, cotton clothing. This allows air to move around your body and keep it cool. Choosing lightweight, breathable, natural fabrics rather than synthetics might also help you avoid irritation and stay comfortable.

The following tips may help to prevent heat rash:

  • Avoid wearing tight clothing that doesn’t allow your skin to breathe. Moisture-wicking fabrics may help prevent sweat buildup on the skin
  • Avoid using thick lotions or creams that can clog your pores.
  • Try not to become overheated, especially in warmer months. Seek out air-conditioning or carry a handheld fan.
  • Use a soap that won’t dry your skin and doesn’t have fragrances or dyes.

Heat rash is rarely serious. Often, it goes away without treatment in a few days. But you should call a doctor if you begin to experience:

You should speak with a doctor if your child has a heat rash that doesn’t resolve in a few days. A doctor may recommend that you apply lotions like calamine or lanolin to relieve itching and prevent further damage. You should keep the child’s skin cool and dry to help relieve the heat rash.

Heat rash causes minor discomfort, spots, itching, and swelling. It usually resolves itself in a matter of days for most people.

You can prevent it by staying cool in warmer climates, wearing loose clothing, and avoiding thick creams.

Talk with a doctor if you believe you may have something more serious or if you have a heat rash that frequently recurs.