Ther terms hyperhidrosis and diaphoresis are often used interchangeably to describe excessive perspiration. Diaphoresis can be used to refer to excessive sweating that occurs with certain diseases (secondary hyperhidrosis). Since the HPO does not intend to provide coess for etiologies or diseases, we will use these terms interchangeably to refer to excessive perspiration without an appropriate cause such as hot and humid weather.