Health A to Z
Prickly heat, also known as miliaria rubra, is an itchy rash of small, raised red spots that causes a stinging or prickling sensation on the skin.
Prickly heat can develop anywhere on the body, but it usually appears on your face, neck, back, chest or thighs a few days after exposure to hot temperatures.
The rash is made up of tiny spots or bumps that are surrounded by an area of red skin.
The spots sometimes look like tiny blisters and can cause:
Prickly heat usually develops when a person sweats more than usual, such as during hot or humid weather. However, it's also possible to get prickly heat in the winter.
The condition is caused when the body's sweat glands become blocked. Excessive sweating can result in sweat becoming trapped beneath your skin. The trapped sweat causes skin irritation and the characteristic heat rash.
The symptoms of prickly heat are usually worse in areas that are covered by clothing. This is because clothing can make you sweat and sometimes causes friction (rubbing).
Although anyone can get prickly heat, you're more at risk of developing it if you're in a hot climate where you sweat more than usual.
The following also increase your risk:
Babies and children are also more at risk of getting prickly heat, because their sweat glands aren't fully developed.
Prickly heat isn't a serious condition and rarely requires any specific treatment. The rash usually disappears after a few days.
However, there are several things you can do to ease your symptoms:
Read more about staying safe in the sun.
If your baby has a rash and appears to be unwell, you should visit your GP or contact NHS 111.
Prickly heat is common in babies and doesn't cause any serious harm. However, if you're concerned, your GP will be able to confirm the cause of your baby's rash and give appropriate treatment.
Read more about skin rashes in babies.