Yohimbine [yo-HIM-bean] is a selective competitive α2 blocker. It is found as a component of the bark of the yohimbe tree and is sometimes used as a sexual stimulant. Yohimbine works at the level of the CNS to increase sympathetic outflow to the periphery. It directly blocks α2 receptors and has been used to relieve vasoconstriction associated with Raynaud's disease. Yohimbine is contraindicated in CNS and cardiovascular conditions because it is a CNS and cardiovascular stimulant.