Heat rash (miliaria) is a skin problem that develops in some people when they sweat more than usual. The rash is also sometimes called prickly heat, or a heat rash, or a sweat rash. It is not usually serious but it can be itchy and uncomfortable.
This is a companion discussion topic for the original article at https://patient.info/skin-conditions/sun-and-sunburn/prickly-heat-and-heat-rash-miliaria