Hyperhidrosis (excessive sweating) can either be generalized or localized to specific parts of the body. Hands, feet, axillae (arm pits), and the groin area are among the most active regions of perspiration due to the relatively high concentration of sweat glands; however, any part of the body may be affected. Primary hyperhidrosis is found to start during adolescence or even before, and interestingly, seems to be inherited as an autosomal dominant genetic trait.

One theory is that hyperhidrosis results from an overactive sympathetic nervous system, but this hyperactivity may in turn be caused by abnormal brain function.