When Your Child Has Heat Rash (Prickly Heat)

Outline of baby from back with shaded areas around neck and on buttocks and inner thighs. Outline of baby from front with shaded areas around neck, in armpits, and in groin.
The shaded areas are common sites of heat rash in babies.

Heat rash (also called prickly heat) is a common problem in children, especially babies. It causes small red bumps on the skin. It appears most often on the neck, buttocks, and skin folds. But it can appear anywhere on the body. Heat rash is not serious. It can easily be treated at home.

What causes heat rash?

Heat rash is caused by blocked sweat glands. This can happen when your child:

  • Is exposed to too much sun or heat

  • Is overdressed (wearing too many layers of clothing)

  • Engages in intense exercise or physical activity

What are the symptoms of heat rash?

Heat rash can cause parts of the skin to turn red and develop small bumps. The skin can also itch.

How is heat rash diagnosed?

Heat rash is diagnosed by how it looks. To get more information, the healthcare provider will ask about your child’s symptoms and past health. The healthcare provider will also examine your child. You will be told if any tests are needed.

How is heat rash treated?

In most cases, heat rash doesn't need treatment. It often goes away on its own within 2 to 3 days. You can do the following at home to help ease your child’s symptoms:

  • Apply over-the-counter (OTC) hydrocortisone cream 1 to 2 times per day to the rash to ease itching. Don't put the steroid cream under the diaper. Each time before and after applying the cream, wash your hands with warm water and soap.

  • Give your child OTC antihistamine medicine to ease itching.

  • Apply a cool compress (such as a clean washcloth dipped in cool water) to the rash.

  • Give your child cool baths.

  • Loosen your child’s diaper if it rubs against the rash area.

Call the healthcare provider

Call your child's healthcare provider if your child has any of these:

  • A heat rash that doesn’t go away within 7 days of starting treatment

  • Other symptoms such as a fever, sore throat, or body aches, which may suggest an illness or infection

  • Fever (see Fever and children, below)

  • A seizure caused by the fever

Fever and children

Use a digital thermometer to check your child’s temperature. Don’t use a mercury thermometer. There are different kinds and uses of digital thermometers. They include:

  • Rectal. For children younger than 3 years, a rectal temperature is the most accurate.

  • Forehead (temporal). This works for children age 3 months and older. If a child under 3 months old has signs of illness, this can be used for a first pass. The provider may want to confirm with a rectal temperature.

  • Ear (tympanic). Ear temperatures are accurate after 6 months of age, but not before.

  • Armpit (axillary). This is the least reliable but may be used for a first pass to check a child of any age with signs of illness. The provider may want to confirm with a rectal temperature.

  • Mouth (oral). Don’t use a thermometer in your child’s mouth until he or she is at least 4 years old.

Use the rectal thermometer with care. Follow the product maker’s directions for correct use. Insert it gently. Label it and make sure it’s not used in the mouth. It may pass on germs from the stool. If you don’t feel OK using a rectal thermometer, ask the healthcare provider what type to use instead. When you talk with any healthcare provider about your child’s fever, tell him or her which type you used.

Below are guidelines to know if your young child has a fever. Your child’s healthcare provider may give you different numbers for your child. Follow your provider’s specific instructions.

Fever readings for a baby under 3 months old:

  • First, ask your child’s healthcare provider how you should take the temperature.

  • Rectal or forehead: 100.4°F (38°C) or higher

  • Armpit: 99°F (37.2°C) or higher

Fever readings for a child age 3 months to 36 months (3 years):

  • Rectal, forehead, or ear: 102°F (38.9°C) or higher

  • Armpit: 101°F (38.3°C) or higher

Call the healthcare provider in these cases:

  • Repeated temperature of 104°F (40°C) or higher in a child of any age

  • Fever of 100.4° (38°C) or higher in baby younger than 3 months

  • Fever that lasts more than 24 hours in a child under age 2

  • Fever that lasts for 3 days in a child age 2 or older

How is heat rash prevented?

You can help prevent your child from getting a heat rash:

  • Remove extra layers of clothing from your child when it’s warm. Children should not wear more than one extra layer of clothing than adults.

  • Dress your child in loose-fitting clothing that does not rub against the skin.

  • Change your child’s diaper right away when it’s wet or soiled.

© 2000-2022 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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