The bark of the West African yohimbe tree is a traditional aphrodisiac and the source of yohimbine, a prescription drug for impotence. It appears to be modestly effective, but it also presents numerous safety risks. Yohimbe should not be used except under physician supervision.

Like the drug yohimbine, the bark of the yohimbe tree is widely used to treat impotence. Many herbalists report that the herb is more effective than the purified drug, perhaps due to the presence of other unidentified active ingredients. However, there have been no studies to evaluate this claim. Furthermore, due to the lack of supervision of herbal products, there are real concerns that herbal yohimbe might contain either too much or too little yohimbine. (See also Safety Issues.)

Yohimbine (the drug) is only modestly effective at best; better than placebo, but only successful in about 30% to 45% of the men who use it.1 Yohimbine has also been evaluated in combination with the supplement arginine.15 A double-blind, placebo-controlled trial of 45 men found that one-time use of this combination therapy an hour or two prior to intercourse improved erectile function, especially in those with only moderate erectile dysfunction scores. Arginine and yohimbine were both taken at a dose of 6 g.

One small, double-blind study of yohimbine combined with arginine found an increase in measured physical arousal among 23 women with female sexual arousal disorder.2 However, the women themselves did not report any noticeable subjective effects. In addition, only the combination of yohimbine and arginine produced results; neither substance was effective when taken on its own.

An open trialof yohimbine alone to treat sexual dysfunction induced by the antidepressant fluoxetine (Prozac) found improvement in 8 out of 9 people, two of whom were women.3 However, in the absence of a placebo group, these results can't be considered reliable; in addition, there are concerns about the safety of combining yohimbe with antidepressants.

Yohimbe is also sometimes recommended for depression. However, its effectiveness is unknown and there are much safer herbs for this purpose, such as St. John's wort.