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Heat Rash (Miliaria)

What is heat rash?

Heat rash is a skin rash that usually occurs on the back, neck, or chest. The rash looks like tiny, pink bumps. Occasionally, some are pinpoint-size water blisters. The rash can be itchy or feel prickly. Heat rash is sometimes called "prickly heat."

What is the cause?

Heat rash is caused by blocked-off sweat glands. Lots of children get it during hot, humid weather when sweat glands are overworked. Infants can also get it in the wintertime with fever or overdressing. Heat rashes are also caused by oils applied to the hair to make it shiny or ointments applied to the chest for coughs. This mainly occurs in infants because the openings of their sweat glands are tiny and can easily become blocked off by ointments or oils. Older children can get heat rashes with exercise.

How long does it last?

With treatment, heat rash usually clears up completely in 2 to 3 days.

How can I take care of my child?

  • Cooling: Use techniques that cool off the skin:
    • Give cool or lukewarm baths, without soap for 10 minutes 4 times per day. Caution: Avoid any chill. Let the skin air-dry.
    • For localized rashes, apply a cool, wet washcloth to the area for 5 to 10 minutes.
    • Dress your child in as few layers of clothing as possible.
    • Lower the temperature in your home or use a fan when your child is asleep.
    • Have the child lie on a cotton towel to absorb perspiration.
  • Hydrocortisone cream: Apply 1% hydrocortisone cream (no prescription necessary) 3 times a day to itchy spots. Avoid hydrocortisone ointments. Calamine lotion is another option.
  • Avoid ointments: Avoid all ointments or oils because they can block off sweat glands. Be sure the rash isn't caused by a mentholated ointment being used for a cough.

When should I call my child's healthcare provider?

Call during office hours if:

  • The rash lasts more than 3 days on this treatment.
  • You have other concerns or questions.
Written by Barton D. Schmitt, MD, author of “My Child Is Sick,” American Academy of Pediatrics Books.
Pediatric Advisor 2013.2 published by RelayHealth.
Last modified: 2012-07-24
Last reviewed: 2012-05-14
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
© 2013 RelayHealth and/or its affiliates. All rights reserved.
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