Heat rash

Dr Lynn Thomas, OStJ, BSc, MB.BS, MA, FRCPClinically reviewed: 28/04/2025

Heat rash is sometimes called prickly heat. Find out what to look for and how to perform first aid.

What is heat rash?

Heat rash consists of small red spots or raised bumps that can cause a stinging or prickling feeling on the skin, sometimes called prickly heat. It occurs when sweat glands are blocked due to the casualty sweating more than normal. It can appear anywhere on the body, but usually appears on the face, chest, back, and thighs.

Signs and symptoms

Someone with heat rash may have:

a rash of tiny red spots, blisters or bumps   
a prickling or burning feeling on their skin
itchy skin
redness and mild swelling.

If they have these symptoms, the rash is not serious and should go in a few days.

What to do

1
Tell them to drink lots of water to prevent them becoming dehydrated.
2
Take a cool bath or shower to cool the skin and prevent further sweating.
Do not use perfumed shower gels or creams as this could irritate the skin.
3
Apply a cold ice pack wrapped in a tea towel for up to 10 minutes.
4
Wear lose clothing, preferably made of cotton, which will not trap the heat as much as synthetic fibres.
5
Suggest they avoid excessive heat such as a fire, heater, or sitting in the sun, to prevent aggravating the rash.
6
Advise them to see a pharmacist or healthcare professional for further treatment if required.
They may prescribe calamine lotion, an antihistamine, or low strength hydrocortisone cream.
7
If they are concerned or unwell, seek medical advice.