What Causes Heat Rash?
High temperatures and muggy weather increase the incidence of heat rash because people increasingly sweat in these conditions. Anything that causes eccrine duct blockages and prevents sweat from reaching the skin’s surface can cause heat rash. FG Trade / Getty Images First Time With Heat Rash: Why? FG Trade / Getty Images Heat rashis most common in hot, humid weather. Heavy bedding or nightclothes can trap the sweat against your skin, causing a heat rash....