Iontophoresis is for people who have extremely sweaty hands or feet (or both). A doctor can prescribe a special iontophoresis machine for you. During iontophoresis, you sit with hands or feet, or both, immersed in shallow trays led with water for about a half-hour while the small machine sends a mild electrical current through the water. Don’t worry, the electric current is safe. No one totally understands exactly how or why iontophoresis works, but scientists believe the electric current and particles in the water work together to invisibly thicken the outer layer of the skin, which blocks the flow of sweat to the surface. The process is repeated every other day for five to ten days, or until sweating is reduced to a comfortable level. Once dry, most people only have to continue doing iontophoresis once a week or even just once a month. If you've tried iontophoresis before and it didn't work, there can be a few reasons why. Sometimes adding baking soda to the tap water can help. Or, a dermatologist can prescribe an anticholinergic to add to the water.