Soaking your feet in strong black tea for 30 minutes a day for a week can help. The acid in the tea kills the bacteria and closes the pores, keeping your feet dry longer. Use two tea bags per pint of water. Boil for 15 minutes, then add two quarts of cool water. Soak your feet in the cool solution. Alternately, you can soak your feet in a solution of one part vinegar and two parts water.
A form of electrolysis called iontophoresis also can reduce excessive sweating of the feet, but requires special equipment and training to administer. In the most severe cases of hyperhidrosis, a surgeon can cut the nerve that controls sweating. Recent advances in technology have made this surgery much safer, but you may notice sweating in other areas of the body after the procedure.