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.
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.
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.