Hidradenitis suppurativa (HS) is a chronic, inflammatory skin disease affecting hair follicles and sweat glands. HS causes abscesses and scarring on the skin, most commonly affecting the armpits, groin, and buttocks. The cause of hidradenitis suppurativa is not known. However, it is thought to be related to an increase in hair follicles that can produce oil (sebum). This increase in sebum production may be caused by hormones such as testosterone and estrogen, and HS is more common in women than in men.