Health Library Heat RashFrom Healthwise

What is heat rash?

Heat rash (prickly heat) is a red or pink rash usually found on body areas covered by clothing. It can develop when the sweat ducts become blocked and swell and often leads to discomfort and itching. Heat rash is most common in babies, but may affect adults in hot, humid climates.

What causes heat rash?

In babies, heat rash can be caused by well-meaning parents who dress their baby too warmly, but it can happen to any baby in very hot weather. A baby should be dressed as an adult would be to be comfortable at the same temperature and activity level. Babies' hands and feet may feel cool to your touch because most of their blood is near the stomach, helping digestion, but that does not mean they need to be dressed too warmly in hot weather.

What are the symptoms of heat rash?

Heat rash looks like dots or tiny pimples. In young children, heat rash can appear on the head, neck, and shoulders. The rash areas can get irritated by clothing or scratching, and, rarely, a secondary skin infection may develop.

How is heat rash diagnosed?

Heat rash can usually be identified by its appearance and does not usually require medical attention. However, if doesn't go away after 3 or 4 days, or if it appears to be getting worse, or if your child develops a fever, contact your health professional right away.

When you or your child has a rash, it is important to watch for signs of infection, including:

• Increased pain, swelling, redness, or warmth around the affected area.
• Red streaks extending from the affected area.
• Drainage of pus from the area.
• Swollen lymph nodes in the neck, armpit, or groin.
• Fever of 100 °F (37.8 °C) or higher, or chills with no other known cause.

If any of these symptoms develop, contact your health professional immediately.

What is the treatment for heat rash?

Most prickly heat rashes heal on their own. The following steps can help relieve symptoms.

• Start by cooling your baby down. Remove or loosen clothing and move him or her to a cool, shady spot.
• Cool the affected areas directly, using cold wet washcloths or a cool bath.
• Let the skin air-dry instead of using towels.
• If your baby's skin is irritable to touch, calamine lotion or hydrocortisone cream may be used with your health professional's approval.
• Avoid ointments or other lotions because they can irritate the skin.

The following tips can help prevent future episodes of the rash:

• Dress your child in as few clothes as possible during hot weather.
• Keep the skin cool and dry.
• Keep the sleeping area cool.

After the rash is gone, gradually expose your child to warmer temperatures so that his or her skin can acclimate.

• Health and Safety, Birth to 2 Years
• Heat-Related Illnesses

Author:	Jan Nissl, RN, BS	Last Updated: August 29, 2006
Medical Review:	Michael J. Sexton, MD - Pediatrics Thomas Emmett Francoeur, MDCM, CSPQ, FRCPC - Pediatrics
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