Yohimbin

Yohimbin, also known as yohimbine, is an indole alkaloid derived from the bark of the West African yohimbe tree (Pausinystalia johimbe) and related species. It has been used in traditional medicine and is marketed in some countries for sexual function and other uses. The compound occurs naturally in small amounts in the plant material and can be obtained as a purified pharmaceutical or as an ingredient in dietary supplements in some jurisdictions.

Pharmacology and effects

Yohimbine acts as a selective antagonist of alpha-2 adrenergic receptors. By blocking these receptors, it can increase sympathetic nervous system activity and the release of norepinephrine, which can influence vascular tone, energy, and arousal. This mechanism underlies both some stimulant-like effects and the potential for increased blood pressure and heart rate.

Medical use and evidence

Historically, yohimbine has been used as an aphrodisiac and was prescribed in some countries for erectile dysfunction. In many places it is not approved as a prescription drug, and products containing yohimbine are sold as dietary supplements with varying quality and dosages. Systematic reviews have generally found only modest and inconclusive evidence for efficacy in sexual dysfunction, and results are mixed with concerns about study bias and heterogeneity.

Safety and regulation

Common adverse effects include increased blood pressure and heart rate, anxiety, insomnia, dizziness, nausea, and sweating. Yohimbine can interact with antihypertensive medications, antidepressants, and monoamine oxidase inhibitors. It is contraindicated in certain medical conditions such as hypertension and heart disease, and its use during pregnancy or breastfeeding is not advised. Regulatory status varies by country: some places restrict or ban its use in supplements, while others require medical supervision for prescription formulations.