Yohimbine is a naturally occurring alkaloid found in the Pausinystalia yohimbe tree and the Rauwolfia serpentina plant. Yohimbine is a stimulatory compound that primarily acts on the alpha-2-adrenergic receptors in the body.^[1] It’s best known for its ability to increase fat burning (lipolysis)^[2] and aid in male sexual dysfunction.^[3] Yohimbine supplementation is also used for weight loss,^[4][5][6] body composition,^[7][6] treatment of phobias,^[8][9] and orthostatic hypotension,^[10] though there is a lack of evidence to support yohimbine’s benefits for many of these conditions.

Some evidence supports the use of yohimbine as a natural way to improve symptoms of erectile dysfunction (ED) in men. While studies have questioned this claim,^[11] two meta-analyses concluded that yohimbine taken alone^[12] or alongside other therapies, including arginine and PDE-5 inhibitors,^[13] improves ED when compared to a placebo, though studies using combined yohimbine and PDE-5 inhibitors have only been conducted in animals.^[14]

Although it’s often marketed as a fat-loss and performance-enhancing supplement for athletes, there’s no evidence that yohimbine improves strength, increases muscle, or enhances physical performance.^[15] Yohimbine does seem to have a lipolytic effect (increases “fat burning”)^[15] and may improve body composition^[6] or cause regional fat loss when used as a topical ointment.^[7]

When taken at the recommended dose (≤0.2 mg per kg of body weight), yohimbine may cause nausea, abdominal pain, dizziness, nervousness, and anxiety.^[16]

Higher doses of yohimbine may be dangerous; a report from 2005 found that yohimbine had the highest rate of toxic effects of any botanical product.^[17] Case reports of excess yohimbine ingestion have suggested that anxiety, hypertension (high blood pressure), tachycardia (high heart rate), arrhythmias, and agitation are among the more severe side effects of this compound.^[15]

Furthermore, many yohimbine-containing supplements in the U.S. were found to be inaccurately labeled — they contained 23%–147% of the yohimbine reported on the label and failed to report the amount of yohimbine contained in the product or warn of the potential harms of excess consumption.^[18]

Yohimbine is a selective alpha-2-adrenergic antagonist. In other words, it targets and inactivates a class of receptors in the nervous system that is responsive to the neurotransmitter norepinephrine (noradrenaline).^[19] Alpha-2 receptor antagonism enhances the sympathetic nervous system release of norepinephrine, causing the stimulatory and “hyperadrenergic” effects of yohimbine.

Antagonism of alpha-2 receptors also inhibits penile smooth muscle contraction and may enhance nitric oxide-mediated smooth muscle relaxation — the combined effects of which promote erection and explain the improvement in ED symptoms after supplementing with yohimbine.^[20] Yohimbine also inhibits the activity of alpha-2 receptors on fat cells — where norepinephrine normally acts to suppress fat release. Inhibition of the antilipolytic effect of norepinephrine allows more lipolysis (fat burning) to occur.^[2]