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.

What Is Yohimbe Used for Today?

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 trial of 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.

Dosage

Yohimbe bark is best taken in a form standardized to yohimbine content so you can properly control your dose of the drug. Unfortunately, label claims for yohimbine content have been frequently found to be inaccurate.16 The usual dose of yohimbine is 15 to 30 mg daily. However, higher doses are not necessarily better, and it appears that some people respond optimally to 10 or even 5 mg daily. Furthermore, while some people appear to respond immediately to a single dose, for others it takes 2 to 3 weeks of treatment to provide significant benefits.

Safety Issues

The following discussion applies to the drug yohimbine, rather than the herb yohimbe. All risks of the drug apply to the herb, and there are additional risks to consider as well. For example, as noted above, the amount of yohimbine in a given sample of the herb may not be accurately reflected on the label.16 Furthermore, additional constituents contained in the herb besides yohimbine might present unique (and unknown) risks of their own.

Yohimbine in any form should not be used by pregnant or nursing women, or those with kidney, liver, or ulcer disease, or high blood pressure. Intake of more than 40 mg a day of yohimbine can cause a severe drop in blood pressure, abdominal pain, fatigue, hallucinations, and paralysis. (Interestingly, lower dosages can cause an increase in blood pressure.) Since 40 mg is not very far above the typical recommended dose, yohimbine has what is known as a "narrow therapeutic index." This means that there is a relatively small dosing range, below which the herb doesn't work and above which it is toxic.

Even when taken in normal dosages, side effects of dizziness, anxiety, hyperstimulation, and nausea are common.

Finally, yohimbine may interact adversely with numerous medications, including tricyclic antidepressants, bupropion, methamphetamine, phenothiazines, clonidine, and other drugs for lowering blood pressure.5-14,17

Interactions You Should Know About

If you are taking: