Yohimbine an alkaloid obtained from the bark of yohimbe that is a weak blocker of alpha-adrenergic receptors and has been used in the form of its hydrochloride.

Yohimbine increases the amount of blood that is allowed to flow into the penis and prevents blood from flowing out of the penis. It can cause an erection. Yohimbine is used to treat and diagnose some types of impotence.