Hyperhidrosis is excessive sweating – that’s the simple definition. You can have excessive sweating all over the body, but the most common areas are the underarms, hands, and the feet, but people can sweat all over the body. It can be mild to severe. Mild forms of hyperhidrosis can be having damp underarms or getting sweaty hands prior to a social event. The other end of the spectrum – severe hyperhidrosis – is sweating so much that sweat drips down from a person’s hands when they hold them up, or the sweat causes intense stains on people’s clothes.