Heat rash, also known as prickly heat, is an itchy, uncomfortable condition caused by blocked sweat glands. A baby’s sweat glands are not as efficient at coping with heat as those of an adult or older child and become overworked more easily. It can appear on any part of the body but is especially common around the neck, buttocks, and anywhere that skin folds. Heat rash usually is not serious and can be both prevented and treated at home.

However, in situations where you cannot prevent heat rash from happening to your baby, it is important to recognise and deal with the symptoms as quickly as possible in order to make your baby comfortable and keep heat rash from disrupting sleep and other behaviours you may be trying to schedule.

What does heat rash look like?

Heat rash looks like small, raised spots on the skin, sometimes accompanied by mild swelling. It will cause your baby to show signs of discomfort. The rash looks red on white skin and can be harder to see and look grey or white on brown and black skin.

Is heat the only cause of heat rash in babies?

Heat is the cause of heat rash in babies, usually because they’ve been in direct sunlight or they are wearing too many layers. However, when sweat glands are blocked by ointment, such as menthol balm applied to a baby’s chest to soothe a cough, it can clog the glands and create heat rash-like bumps even when a baby doesn’t seem overheated.

How is heat rash diagnosed?

Heat rash is diagnosed by the way it looks, as described above.

How can I treat my baby’s heat rash?

Heat rash should go away on its own within two to three days. There are some things you can do to keep your baby comfortable in the interim.

Move your baby to a cool (not cold) environment and dress them in breathable clothing. Loosen nappies if they appear to be rubbing against inflamed areas. Bathe your baby in cool water, using perfume-free baby products.

Do not use talc to attempt to heal heat rash; it will be ineffective and may cause irritation. You may be able to apply calamine lotion or hydrocortisone cream to your baby’s heat rash to soothe the skin, but please ask your doctor before doing so and follow application guidelines precisely.

Do not give your baby antihistamines. A doctor may prescribe a liquid antihistamine for a baby over the age of one in some cases.

When should I call a doctor about my baby’s heat rash?

You usually don’t need to call a doctor about the heat rash itself but see medical help if your baby also has one or more of the following symptoms:

Persistence of the rash beyond three days after you start treatment
Flu-like symptoms: sore throat, runny nose
The rash begins to look infected—expelling pus or becoming more red and inflamed.
A temperature of or above 38C (use a digital thermometer to monitor your baby’s temperature)
A seizure

How can I stop my baby from getting heat rash?

Keep them away from the direct sunlight, especially at peak times (10a.m. to 4 p.m.).
Use air conditioning in doors when in a hot climate (while keeping your baby away from direct air and ensuring the room they are in is temperate).
Keep your baby well hydrated.
Dress them in comfortable, loose fitting clothing.
Avoid disposable nappies with PVC plastic that doesn’t let your baby’s skin breathe.
Change your child’s nappy right away when it is wet or soiled.

Remember, while heat rash is usually unserious and goes away by itself, if you are especially concerned about your child and want to ask a doctor to look at them, it’s always best to trust that instinct. You know your child better than anyone, and parental instincts are very valuable.

For more information on supporting your baby’s wellbeing, take Unii’s Baby Health Journey video course with Dr. Su Laurent.

What should I do if my baby has heat rash?

Unii looks at prickly heat, an especially uncomfortable condition for a baby.