About Herbs

Bottom Line: An active component of yohimbe has been shown to be effective in treating erectile dysfunction. Several clinical trials have been performed to support this data.

Yohimbe is a tree native to West Africa. Yohimbine, an alkaloid derived from the bark of Yohimbe tree has been used for many years as an aphrodisiac and in the treatment of erectile dysfunction. It can also cause side effects including nervous excitation, tremors, high blood pressure, nausea, and vomiting.

Treatment of erectile dysfunction:
In a recent review of several clinical trials, yohimbine was found to be effective compared to placebo in the treatment of erectile dysfunction.

Pausinystalia yohimbe

Yohimbe Bark, yohimbine hydrochloride, Johimbe, aphrodine, corynine, quebrachine

Derived from the bark of a tree native to West Africa. This herb has been used mainly as an aphrodisiac. Marketed as a steroid substitute, yohimbe is also used with other supplements in formulas for athletic performance. The active component, an alkaloid called yohimbine, has been used in clinical studies to treat sexual dysfunction in men and women ⁽⁵⁾. Oral administration is well tolerated, but long-term toxic effects have not been studied. Following absorption, yohimbine is rapidly metabolized. Yohimbine stimulates the central nervous system and also acts as a monoamine oxidase inhibitor and calcium channel blocker. Thus, it can potentially interact with numerous drugs causing severe adverse effects. Although yohimbine has been shown to be an effective treatment for erectile dysfunction in some clinical trials ^{(2) (3) (4) (5)}, it can also cause side effects including nervous excitation, tremors, high blood pressure, nausea, and vomiting.

Yohimbine is an alpha₂-adrenoreceptor antagonist and it increases the plasma levels of noradrenaline by increasing noradrenaline release from the sympathetic nervous system ⁽⁵⁾. Blocking of alpha₂-adrenoreceptors results in increased blood supply to cavernous body tissue. Yohimbine increases catecholamine release in peripheral tissues that is unrelated to sympathetic stimulation. Aphrodisiac activity of yohimbine may be caused by its dilation effect on the genital blood vessels, and the enhancement of sensation to genital tissue and an increased reflex excitability in the sacral region ⁽⁵⁾.

Yohimbine has a rapid onset due to its highly lipophilic property which assists its absorption and crossing of the blood-brain barrier in a short period of time. Peak plasma levels were observed within 10 to 45 minutes of oral administration. The average oral bioavailability is 33% (ranging from 7% to 87%). It is rapidly eliminated with a half-life of 0.58 hr following oral intake ⁽⁷⁾. Less than 1% of administered yohimbine is excreted unchanged in urine.

Although a few clinical trials have shown yohimbine to be a safe initial intervention in the treatment of erectile dysfunction, more well-designed studies are needed to establish its use.

Montorsi, F et al. Effect of yohimbine-trazodone on psychogenic impotence: A randomized, double-blind, placebo-controlled study.Urology1994;44(5):732-736.
Sixty-three patients diagnosed with psychogenic impotence were randomly administered either a combination of 15mg yohimbine and 50mg trazodone or a placebo for 8 weeks. Patients who initially received yohimbine were then switched to placebo and those who received placebo were given the combination of yohimbine and trazodone for 8 more weeks. 71% of the patients showed positive response to the drug treatment that was statistically better than placebo. More than half of the patients maintained the positive results after six months. Researchers concluded that the combination of yohimbine and trazodone is safe and effective treatment for psychogenic impotence.

Pekka K et al. Is high-dose yohimbine hydrochloride effective in the treatment of mixed-type impotence? A prospective, randomized, controlled, double-blind crossover study. Urology 1997;49:441-444.
Twenty-nine patients with mixed-type impotence were randomly assigned to receive 36 mg of yohimbine or placebo for 25 days. After a 14 day interval, the patients who received placebo were switched to yohimbine and patients who received yohimbine were switched to placebo respectively. This treatment continued for another 25 days. Researchers found no statistical difference between these two groups and concluded that yohimbine is not an effective treatment as a first-line treatment for mixed-type impotence.

Ernst, E., and Pittler, M. H. Yohimbine for erectile dysfunction: A systematic review and meta-analysis of randomized clinical trials. J. Urol 1998;159(2):433-436.
This review included seven clinical trials that were performed to determine the therapeutic efficacy of yohimbine for erectile dysfunction. The trials indicate yohimbine is clinically effective compared to placebo and the benefits seem to outweigh the risks. There were very few adverse reactions reported. Researchers suggest that yohimbine can be used as a primary intervention in the treatment of erectile dysfunction.