Sweating is your body’s way of regulating its temperature. People with hyperhidrosis sweat much more than they need to, even when their body isn’t overheated because they’re in a hot environment or being physically active.
An estimated 10 million people in the U.S. (and 90% of the people who present with excessive sweating) have primary axillary hyperhidrosis (excessive sweating in their armpits). Other common areas are the hands and feet, but some people also experience it on the face, on the scalp, between the breasts, in the groin, on the lower back, or on the buttocks.
According to the Cleveland Clinic, hyperhidrosis usually involves overactive eccrine glands, several million of which are distributed across the body. These glands secrete odorless, clear sweat that helps cool you down (odor occurs when bacteria on the skin break the sweat down). When they overreact, they produce more sweat than your body needs.