This herb is derived from the bark of an African evergreen tree and contains an active alkaloid called yohimbine. It is most widely known for its potential use in the treatment of erectile dysfunction. This is due to the herb's ability to cause dilation of smooth muscles, which leads to vasodilation and increased blood perfusion. However, it is important to note that Yohimbe has multiple effects in the body, and while it may act to dilate vessels in some areas, it can cause vasoconstriction in others. There is some evidence to suggest that Yohimbe also has antidepressant effects. Yohimbe should not be combined with tri-cyclic antidepressants, but it has been shown to improve the antidepressant effect of SSRI antidepressants.