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Heat Rash

Pediatric Dermatology Basics

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Updated May 22, 2014

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Although having a heat rash is common, it is likely not as common as many parents believe, who tend to call any red rash their kids have when it is hot outside a heat rash.

Learning to distinguish heat rash from other common skin rashes, such as impetigo, eczema, folliculitis, and poison ivy, can be helpful so that you can properly treat and prevent this common rash.

As the name implies, heat rash is triggered in certain children when they become overheated, either because they are overdressed or because it is simply too hot outside. As they become hot and sweat, their sweat ducts become blocked and rupture.

Prickly Heat

Prickly heat or miliaria rubra is the most common type of heat rash. In this form of heat rash, the sweat duct becomes red and inflamed, and may cause a 'prickling' or stinging sensation. This type of heat rash may also cause mild itching.

The inflamed sweat ducts look like small bumps with a red halo around them and can usually be found grouped together under a child's clothing and inside the folds of his skin, such as his neck, armpits, and groin. Infants who wear a hat may also get a heat rash on their forehead and scalp.

Miliaria Crystallina

Just like prickly heat, this type of heat rash occurs when the sweat ducts become blocked and rupture. These sweat ducts are closer to the skin surface though and don't get inflamed, leading to the classic appearance of small clear vesicles on the child's skin, without any redness or other symptoms, typically on their neck, head, or upper chest.

Preventing Heat Rash

Most methods of preventing heat rash have the goal of not allowing your child to get overheated and include:
  • dressing your child in weather appropriate, loose fitting clothing, so that he doesn't get overheated.
  • avoiding excessive heat and humidity when possible.
  • avoiding occlusive ointments, including moisturizers, or oil based products on a child's skin, which can also block the sweat ducts.

Heat Rash Treatments

Although heat rash usually goes away on its own in a few days, some children do require treatment, which can include:
  • removing the child from the triggering environment, such as dressing in less clothing, moving inside to a cooler, air conditioned environment, etc.
  • mild strength topical steroids, although these usually aren't needed
  • calamine lotion
  • compresses with cool water
  • antibiotics for secondary infections

What You Need To Know

  • Heat rash is also called miliaria.

  • Heat rash is most common in babies and young infants when they become overheated, either because it is too warm outside or they are simply overdressed or have a fever.

  • Miliaria profunda occurs in people who have repeated episodes of prickly heat.

  • Miliaria pustulosa refers to a case of prickly heat that gets infected.

  • Folliculitis is often confused with prickly heat, but unlike folliculitis, the rash of prickly heat does not involve hair follicles.

Sources:

Habif: Clinical Dermatology, 4th ed., Copyright © 2004 Mosby, Inc.

Behrman: Nelson Textbook of Pediatrics, 17th ed., Copyright © 2004 Saunders, An Imprint of Elsevier.

Skin lesions in the neonate. Conlon JD - Pediatr Clin North Am - 01-AUG-2004; 51(4): 863-88, vii-viii.

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