What is heat rash? Learn the causes and symptoms

Sweat production is one of the ways your body can regulate its own temperature. Sweat is produced by small glands located throughout your body. Regulated by the brain, these glands release sweat via ducts on your skin. The sweat then evaporates to help cool down your body.

Heat rash occurs when sweat ducts become clogged and inflamed. Blocked ducts cannot release sweat, causing moisture to become trapped beneath the skin surface. This causes rash-like symptoms, such as raised bumps, coarse skin texture, and discomfort.

Knowing how to spot heat rash can help you and your doctor pinpoint the best heat rash treatment.

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What Causes Heat Rash?

Heat rash, also called “prickly heat” or “miliaria” is a skin condition that can affect babies, children, and adults in hot weather. The rash usually occurs when your sweat ducts become blocked and perspiration is trapped under your skin. People often experience this condition in the summer or in humid climates.

Babies are especially susceptible to this condition when their parents dress them in clothing that is too heavy for the temperature. Adults, however, can also experience heat rash when they overdress or spend too much time outside in hot and humid weather.

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Identifying Heat Rash Symptoms

Heat rash is sometimes referred to as “heat stress.” Its symptoms are easy to detect.  common sign is a cluster of red bumps that resemble pimples on the skin. The red bumps, which can look like blisters, typically pop up on the neck, chest, and arms.

They tend to accumulate in places with creases, such as elbow creases, armpits or under the breasts. Some types of heat rash can make you feel an itchy or prickly sensation on your skin. There are different forms of heat rash that can range in severity, so if you think you might have heat rash, consult your doctor. Symptoms may include:

  • Bumpy, itchy, and/or blister-like rash.
  • Flesh-colored bumps
  • Burning sensation along skin
  • “Crawling” or prickly sensation on skin
  • Itchy sensation on skin
  • Pus formation around blisters or lesions

Heat Rash Treatment

The best treatment depends on the severity of the rash. In many cases, removing yourself from the warm environment to a cooler, less humid atmosphere can resolve the issue, according to the Centers for Disease Control. Consider using a dusting powder to promote comfort, and an anti-itch cream can also help relieve itching and discomfort.

If your rash symptoms worsen or last longer than a few days, it may be time to visit your doctor. Prolonged symptoms could mean the heat rash has become infected. Look for signs of infection, such as pus, increased pain, swelling, warmth around the affected area, swelling, swollen lymph nodes, a fever, or chills.

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Heat rash is a treatable condition when you know what to look for and how to take care of it. For more information on heat-related illnesses and how they affect skin care, contact the UPMC Department of Dermatology.

About UPMC

Headquartered in Pittsburgh, UPMC is a world-renowned health care provider and insurer. We operate 40 hospitals and 700 doctors’ offices and outpatient centers, with locations in central and western Pennsylvania, Maryland, New York, and internationally. We employ 4,900 physicians, and we are leaders in clinical care, groundbreaking research, and treatment breakthroughs. U.S. News & World Report consistently ranks UPMC Presbyterian Shadyside as one of the nation’s best hospitals in many specialties and ranks UPMC Children’s Hospital of Pittsburgh on its Honor Roll of America’s Best Children’s Hospitals.