heat rash
From Longman Dictionary of Contemporary EnglishRelated topics: Illness & disabilityheat rashˈheat rash noun [countable, uncountable] MIpainful or itchy red spots on someone’s skin caused by heatExamples from the Corpusheat rash• One of his powders was good for heat rash.• Several monitors have come down with heat rash and heat stroke this summer.