Heat Rash

1. Heat Rash Slideshow Pictures
2. Summer Skin Hazards Slideshow Pictures
3. Dehydration Tips Slideshow Pictures

Medical Author:

Benjamin Wedro, MD, FACEP, FAAEM

Benjamin Wedro, MD, FACEP, FAAEM

Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

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Medical Editor:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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• Heat rash occurs when the skin's sweat glands are blocked and the sweat produced cannot get to the surface of the skin to evaporate. This causes inflammation that results in a rash.
• The rash appears as reddened skin with tiny blisters and is due to inflammation. It often occurs in skin creases or areas of tight clothing where air cannot circulate.
• The rash may be itchy or cause a prickly sensation and therefore it is also known as prickly heat.
• Heat rash usually fades when the skin is allowed to cool. Medical treatment is necessary only if the area becomes infected.
• Heat rash can be prevented by avoiding hot, humid conditions, wearing lose fitting clothes and using air conditioning or fans to allow air to circulate.

The skin's job is to protect the inside of the body from the outside world. It acts as a preventive barrier against intruders such as pathogens that cause infection, chemicals, or ultraviolet light from invading or damaging the body. It also plays an important role in the body's temperature control. One way that the body cools itself is by sweating, and allowing that sweat or perspiration to evaporate. Sweat is manufactured in sweat glands that line the entire body (except for a few small spots like fingernails, toenails, and the ear canal).

Sweat glands are located in the dermis or deep layer of the skin, and are regulated by the temperature control centers in the brain. Sweat from the gland gets to the surface of the skin by a duct.

A heat rash occurs when sweat ducts become clogged and the sweat can't get to the surface of the skin. Instead, it becomes trapped beneath the skin's surface causing a mild inflammation or rash.

Heat rash is also called prickly heat or miliaria.