There is no definitive answer to this question, but there are a number of theories. Firstly, the electrical current and mineral particles in the water act together to thicken the outer layer of the skin, thereby blocking the flow of sweat. Once output is blocked or interrupted, sweat production in the treated area stops. Another theory is that it may temporarily cause a functional impairment of the sweat duct; either by completely blocking sympathetic nervous system transmission to the gland, or changing the cellular secretory physiology. Some believe that it causes a plug on the sweat gland and others believe it induces an electrical charge in the gland that disrupts secretion. Finally, some believe that this treatment decreases the ph in the sweat duct, which may contribute to eccrine gland dysfunction.