Iontophoresis is an effective treatment for the treatment of excessive sweating of the hands and feet. It’s been used since the 1940s, so it’s well tried and tested. It's particularly useful for people who've tried prescription or clinical-strength antiperspirants, but found them ineffective.
The procedure is safe and painless. The affected area (hands/feet) are placed in a shallow pan of water, and a small electrical current is passed through it, and therefore through the surface of the skin. There are no significant or serious side effects and the benefits are long-term, provided you stick with the treatment schedule your doctor recommends (usually once per week).