What is heat rash?

Heat rash is one of many different types of rash. Rash is a symptom that causes the affected area to turn red and blotchy and swell. The rash may cause spots that are bumpy, scaly, flaky, or filled with pus. Rashes can vary in location, pattern and extent and may occur in any area of the body.

Heat rash, also called prickly heat or miliaria, occurs when sweat becomes trapped under your skin. Sweating is a self-regulating mechanism your body uses to maintain a constant temperature. Your sweat-producing glands are located in the middle layer of the epidermis, which is the outer layer of skin. If these glands become clogged and are unable to function, a rash may appear in the affected area. The rash may take one of several forms; it may be clear, skin-colored or reddened.

Heat rash can occur for a variety of reasons, such as wearing too much clothing or using blankets when hot. An individual’s anatomy can also lead to heat rash if there are folds or creases between areas of the skin where sweat can collect. Lotions and creams can clog the pores, along with the sweat glands, as well, producing heat rash.

The trapped sweat leads to the development of clear, raised bumps that indicate the areas of blockage. These bumps are usually not itchy if they occur as a result of a blockage toward the top layer of skin. Repeated or prolonged outbreaks can lead to an infection in the deeper layers of the epidermis and produce itchy, flesh-colored bumps.

Although heat rash itself is generally not serious, it may be a symptom of heat stroke, a life-threatening condition that, left untreated, can lead to organ failure. Seek immediate medical care (call 911) for serious symptoms, including high fever (higher than 101 degrees Fahrenheit); extreme thirst and dehydration; flushed appearance; weakness; rapid heart rate; shallow, rapid breathing; or changes in mental status, such as confusion or forgetfulness.


What are the symptoms of heat rash?

Symptoms of heat rash include the appearance of raised bumps on your skin in the affected area that may range in color from clear to red. The type and color of rash depend on the location in the skin where sweat glands are clogged, and symptoms have a range of severity. The mildest form is called miliaria crystalline (clear, raised rash), a blockage of the sweat glands at the top layer of the s... Read more about heat rashsymptoms


What causes heat rash?

Heat rash occurs when sweat becomes trapped under your skin.

Your sweat-producing glands are located in the middle layer of the epidermis. They can become clogged if you are wearing too much clothing (for example, when it is hot outside). Your anatomy can also predispose you to heat rash if you have folds or creases between areas of the skin where sweat can collect. Lotions and cr... Read more about heat rashcauses


How is heat rash treated?

The best way to treat heat rash is to ensure that you get plenty of air circulation around your skin. This means wearing light, loose clothing that will let your skin “breathe.” Staying cool and drinking lots of water can help minimize your symptoms and prevent heat rash from progressing to heat stroke.

Treatments for heat rash

If your heat rash does not resolve, some t... Read more about heat rashtreatments

Medical Reviewer: William C. Lloyd III, MD, FACS Last Annual Review Date: Aug 23, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Skin, Hair and Nails

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