The purpose of this study is to find out if taking a birth control pill, YAZ, is safe and effective for treating hidradenitis suppurativa. Hidradenitis suppurativa (HS) is a chronic (long lasting) skin disorder that mostly affects the armpits and groin area. It appears as blackheads and one or more red, tender bumps that may enlarge, break open, and drain pus. Scarring may result after several attacks of the disease.