During this treatment, you sit with your hands, feet, or both in a shallow tray of water for about 20 to 30 minutes, while a low electrical current travels through the water. No one knows exactly how this treatment works, but experts believe it blocks sweat from getting to your skin's surface. You'll have to repeat this treatment at least a few times a week, but after several times you may stop sweating. Once you learn how to do iontophoresis, you can buy a machine to use at home. Some people only require a couple of treatments a month for maintenance.