Understanding Heat Rash

by Eileen Bailey Health Writer

It's summer time and that means hot, humid, sticky weather - the kind of weather that makes you more at risk of developing miliaria or heat rash, sometimes called prickly heat. Heat rash is caused by clogged or immature sweat glands. Perspiration gets trapped under the skin, causing inflammation and irritation, which shows up as a red or pink rash. This type of rash is most common in newborns however, people of any age can get heat rash during hot, humid weather.

Types of Heat Rash

There are three main types of heat rash. No matter which type, the rash usually appears on the neck, shoulders, chest, armpits, elbow creases and groin. It may also appear on any part of the body where clothing causes friction. Each type also has specific symptoms.

Miliaria Crystallina

This type affects the sweat ducts in the top layer of your skin. The rash has clear, fluid filled blisters. These blisters are not itchy or painful. Usually, no medical treatment is necessary as it will clear up on its own.

Miliaria Rubra

This type also occurs in the outer layer of your skin but deeper than miliaria crystalline. It is this type that is also referred to as prickly heat. Infants can develop this rash within the first few weeks of life, however, adults can also develop it, especially during hot, humid weather or if confined to bed rest.

The rash has red bumps which can be itchy or cause a prickly feeling. The areas where the rash develops will not have any perspiration.

Miliaria Profunda

This type of heat rash usually occurs in adults who have had previous episodes of miliaria rubra. It occurs in the dermis, or lower layer of skin, and can appear after activities which cause sweating. The rash is flesh-colored and may resemble goose bumps. If you have this type of heat rash, you may also experience heat exhaustion, including dizziness, nausea and increased heart rate due to lack of perspiration.


Most cases of heat rash do not require any medical treatment and will go away on their own within a few days. FamilyDoctor.org lists the following home treatments:

  • Stay cool. Avoid being outside when it is hot and humid. Try to stay in air-conditioned places, use fans or use cool compresses to keep your skin cool.

  • Keep areas affected by heat rash dry. Use fans to dry your skin and to reduce sweating.

  • Wear loose clothing. Heat rash can develop when clothing rubs against your skin. Loose fitting clothing can help reduce friction from clothing.

  • Use over-the-counter medications, such as acetaminophen, to treat fevers and anti-itch ointments to help with itching

In some cases, you may need to see a doctor for your heat rash. Use the following as a guide to determine if you should contact your physician:

  • If the rash lasts more than 3 or 4 days

  • If the rash continues to worsen

  • If the area affected by the rash is swollen

  • If the rash oozes pus

  • If itchiness is severe

  • If you are dizzy, nauseous, confused or have trouble breathing

Whether your symptoms are mild or severe, if you are uncomfortable and your rash is interfering with your daily activities, talk with your doctor.

More info on rashes:

Understanding Hives

A Rash or Skin Allergies?

Three Rashes You Should Not Ignore


"Heat Rash," Date Unknown, Staff Writer, CNN Health

"Heat Rash," Reviewed 2011, Feb, Staff Writer, FamilyDoctor.org

"What is Heat Rash? What is Prickly Heat? What Causes Heat Rash?, 2010 March 7, Staff Writer, Medical News Today

Eileen Bailey
Meet Our Writer
Eileen Bailey

Eileen Bailey is an award-winning author of six books on health and parenting topics and freelance writer specializing in health topics including ADHD, Anxiety, Sexual Health, Skin Care, Psoriasis and Skin Cancer. Her wish is to provide readers with relevant and practical information on health conditions to help them make informed decisions regarding their health care.