Collagenase Clostridium histolyticum injection (Xiaflex) is used to treat Dupuytren's contracture (a painless thickening and tightening of tissue [cord] beneath the skin in the palm of the hand, which may make it difficult to straighten one or more fingers) when a cord of tissue can be felt upon examination. Collagenase Clostridium histolyticum injection (Xiaflex) is also used to treat Peyronie's disease (a thickening of tissue [plaque] inside the penis that causes the penis to curve). Collagenase Clostridium histolyticum injection (QWO) is also used to treat cellulite (fat deposit beneath the skin) in the buttocks of adult women. Collagenase Clostridium histolyticum injection is in a class of medications called enzymes. In people with Dupuytren's contracture, it works by helping to break down the cord of thickened tissue and allows the finger(s) to be straightened. In people with Peyronie's disease, it works by helping to break down the plaque of thickened tissue and allows the penis to be straightened. In women with cellulite, it works by releasing fibrous bands, redistributing fat cells, and stimulating the growth of new collagen.