Studies and case reports on excessive sweating frequently state that hyperhidrosis is a disease whose origin and mechanism are unknown. However, the term excessive is rarely based on systematic diagnostic measurements, instead being a description of the symptoms from patient histories, which suggests that hyperhidrosis is purely a problem involving the quantity of sweat, whereas it is a change in the control mechanism of sweating in which the need for and production of sweat are strongly disproportionate. This lack of proportion is perceived by those affected to be a limitation of activities of daily living and is thus pathologic.