Prickly heat (heat rash)

What is prickly heat?

Prickly heat is also called heat rash or miliaria. It usually goes away by itself after 2 to 3 days and is harmless. Prickly heat often presents as a red, slightly swollen rash with lots of small, red spots that can feel itchy.

What are the symptoms of prickly heat rash?

Prickly heat can lead to an itchy, prickly rash made with lots of smaller, red spots. 

• Small, red and sometimes raised spots

• An itchy or ‘prickly’ feeling

• Some mild swelling

Symptoms of prickly heat will often go away by themselves after 2 or 3 days after moving to a cooler environment. 

What causes a prickly heat rash?

Prickly heat is caused by blocked sweat glands, which are found beneath the surface of your skin. The blockage causes sweat to become trapped in the nearby skin creating small pockets of swelling. This then leads to a visible rash. 

How is prickly heat diagnosed?

A doctor can diagnose prickly heat by looking at the rash and asking you some questions about when it appeared.

How to treat prickly heat

Prickly heat will often clear up by itself 2 or 3 days after leaving a hot, humid environment and avoiding anything that triggers the heat rash. Keep your skin cool by wearing loose cotton clothing, taking cool showers and baths, using light bedding and drinking plenty of fluids. 

If the rash feels itchy or prickly, try to avoid scratching it. You can calm the rash down by applying a damp cloth to the area for up to 20 minutes and avoiding using scented shower gels and creams on the area. Make sure you wear sunscreen without added scents on sensitive areas as this can make prickly heat worse. 

Remedies like antihistamine tablets or calamine lotion can be helpful to treat a heat rash. A doctor or pharmacist can help advise you on the appropriate treatments to use. In some cases they may advise a weak steroid cream to settle your symptoms. 

Prickly heat in children

Newborn babies are prone to prickly heat, which often occurs around the nappy area, skin folds or on the face. The rash usually clears after a couple of days in newborns.

To treat heat rash in a child, it’s important to keep them cool and dry. Dress your child in light cotton clothing and change any wet or sweaty clothes regularly. Some people may put powder on the area at risk of prickly heat, but it’s important to dry the area well first and make sure the powders are not scented before applying them. 

When should I seek help?

Speak to a doctor or pharmacist to get advice about the best treatment to use on your heat rash. If your baby has a rash that you are worried about, book an appointment with a doctor.