Excessive sweating of the feet is called hyperhidrosis. It's more common in men than in women, and more common in young adults than older adults. People whose feet sweat excessively often also have problems with excessive sweating of the palms. Excessive sweating of the feet seems to be an inherited problem. No one knows exactly why it occurs, but people who sweat excessively seem to have a different “set point” than other people. Most people sweat when it's hot out, or when they become warm. People with hyperhidrosis sweat excessively almost all the time.

The most obvious symptom of hyperhidrosis is feet that sweat excessively. Some people sweat so much that their feet may slip around inside their shoes. The feet may also have a whitish, wet appearance; sometimes, foot infections are present as well. (Constant wetness breaks down the skin, allowing infection to set in.) Foot odor is common. Those suffering from hyperhidrosis may also experience emotional stress and worry regarding foot odor. Sweat-related anxiety and isolation can be particularly severe among teens with plantar hyperhidrosis.