What is heat rash?

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.

woman wearing a straw hat at the beach
Aliaksandr Barysenka/EyeEm/GettyImages

What does heat rash look like?

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
  • 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

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.

Pictures

These images show the difference between the three types of heat rash.VIEW GALLERY2

Treatment of heat rash

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 1-2 times a day can help soothe itching.
  • OTC antihistamines can also take an effect against itching.

8 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:

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. Take a colloidal oatmeal bath. A 2015 studyTrusted Source of colloidal oatmeal extract suggests that the possible anti-inflammatory and antioxidant effects of oat might be behind its potential itch-soothing effects.
  6. Use topical pine tar. Used by people to manage skin conditions for thousands of years, applying pine tar to itchy or inflamed areas can reduce itching and inflammation, according to one 2016 reviewTrusted Source.
  7. Apply Aloe vera gel to the area. Aloe vera is another well-established topical remedy for skin ailments that may help soothe your itchy skin.
  8. Mix sandalwood with water and applying the paste to your heat rash. An older 2011 study found that sandalwood, a herb common to Ayurvedic traditional medicine, might help you reduce inflammation across a number of skin conditions.

Symptoms 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

On lighter skin

The spots may appear red.

On darker skin

The spots can be more understated and harder to identify on darker skin. 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.

For people with darker skin, the spots might appear as white globules with darker halos around them.

What causes heat rash?

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.

Wearing certain types of clothing can trap sweat, leading to heat rash. 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.

Friction on the surface of the skin often causes heat rash. 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.

Risk factors

Having certain health problems or engaging in certain lifestyle choices can increase your risk for heat rash, includingTrusted Source:

  • being prone to intense sweating
  • regularly engaging in high-intensity physical activity
  • taking drugs that trigger sweating like bethanechol, clonidine, and neostigmine
  • Morvan syndrome, a rare genetic disorder that causes excessive sweating
  • type 1 pseudohypoaldosteronism, a condition that causes a loss of sodium through the sweat glands that has some links to heat rash

When should you call your doctor?

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

  • a fever
  • chills
  • increased pain
  • pus draining from the bumps

Call your child’s doctor if your child has a heat rash that doesn’t resolve in a few days. Your doctor may recommend that you apply lotions like calamine or lanolin to relieve itching and prevent further damage. Keep their skin cool and dry to help relieve heat rash.

Prevention

Follow these tips 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.
  • 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 or carry a handheld fan.
  • Use a soap that won’t dry your skin and doesn’t have fragrances or dyes.

The bottom line

Heat rash causes minor discomfort, spots, itching, and swelling. It usually resolves itself in a matter of days for most people. There are several types that look slightly different than one another.

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

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

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