Herb Profile: Yohimbe

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Yohimbe comes from the bark of a tree that grows in the West African region.

In these days of Viagra, the recently approved impotence pill, interest in herbal aphrodisiacs seems to be waning. When faced with impotence, even consumers who generally prefer natural substances are likely to choose a more predictable synthetic alternative. Nevertheless, some interest still exists in the herb yohimbe, which is thought by some to treat impotence.

Yohimbe is derived from the bark of a West African tree called Pausinystalia yohimbe that grows in Cameroon, Gabon, and Congo. For centuries, yohimbe bark was reputed to restore erections to impotent men. Scientists scoffed, but several studies during the 1980s showed that a chemical in the bark, yohimbine, did indeed raise erections in some impotent men by increasing blood flow into the penis.

Despite this recent research and the herb’s traditional use, yohimbe is surprisingly absent from many important historical herbal references and recent major English-language works on the medicinal plants of Africa. According to Herbs for Health editorial adviser James A. Duke, Ph.D, yohimbe’s reputation appears to have come from a different source: German books on herbal medicines, including Hager’s Handbook. The handbook notes that the herb is an aphrodisiac in addition to being useful in treating painful menstruation and prostate inflammation with bladder complaints, and serving as a local anesthesia for eye, ear, and nose operations. In the United States, yohimbe’s use as an herbal remedy appears to have started in the early 1970s, when plants reported to enhance sexual desire or somehow affect the psyche were brought to the forefront by the counterculture.

A Compound Emerges

Recent interest in yohimbe has come largely from medical use of yohimbine, the bark alkaloid once widely used as a prescription drug. Much of the controversy surrounding yohimbe has resulted from equating the bark with the drug. Yohimbine is synthesized in the laboratory, from the bark itself.

Some years ago, the U.S. Food and Drug Administration (FDA) approved yohimbine as a treatment for impotence. The compound is now available in eleven prescription drugs, including Aphrodyne, Erex, Yocon, Yohimex, and Yovital.

Yohimbine was discovered in 1896, and the first physiological study on the compound appeared in 1900, when researchers found that it’s an active excitant to sexual organs in both animal and human studies. Another study published at the same time reported conflicting results, however, concluding that yohimbine did not produce aphrodisiac effects in either humans or animals. Since that time, the aphrodisiac attributes of both yohimbine and yohimbe have remained controversial.

A prescription drug containing synthesized yohimbine hydrochloride has been available for decades. It has been used as an alpha-adrenergic blocker and has an antidiuretic action. To stimulate erection, it has been combined with strychnine, thyroid, methyltestosterone, caffeine, and other substances.

A 1981 letter to the editor of the Journal of the American Medical Association stimulated new interest in the drug yohimbine after reports that it successfully treated impotence in four out of six diabetic patients. Then a 1984 animal study on rats concluded that the alkaloid did increase sexual arousal of animals. A recent review of sixteen studies shows that yohimbine is an effective treatment for erection impairment. Yohimbine affects the autonomic nervous system and helps with male erection by increasing blood flow to the penis.

Yohimbine prescriptions are generally accompanied by some cautions. It’s not to be used if liver or kidney disease is present, and it’s considered a monoamine oxidase (MAO) inhibitor, so tyramine-containing foods such as cheese, liver, and red wine should be avoided. Participants in some clinical trials on the whole herb reported side effects, including anxiety, increased heart rate, elevated blood pressure, flushing, hallucinations, and headaches.

Where’s The Yohimbine?

Since its FDA approval, yohimbine has continued to be assailed by some medical naysayers as ineffective. And they may have a point, at least about the yohimbine products sold in supplement shops and health-food stores.

In 1995, the FDA sponsored a study of twenty-six over-the-counter yohimbine products, among them Super Man, Hot Stuff, and Yohimbe Concentrate. Researchers found only trace amounts of yohimbine in the products tested, ranging from less than 0.1 to 489 parts per million (ppm), probably not enough to have much effect, and considerably less than the yohimbine content of yohimbe bark, which is 7,089 ppm. If you want yohimbine’s benefits, go with either the bark from a source you trust, or with a prescription drug.

The Many Facets Of Arousal

It’s important to understand that compounds that aid erection–no matter whether they’re herbal medicines or pharmaceuticals–are not aphrodisiacs per se. There’s a difference between male erection and male sexual arousal. And these compounds may cause other problems too; the erection drug Viagra has spawned a new sex problem in women–“viagravation,” the irritation women feel when their chemically erect lovers won’t leave them alone. This sort of lesson could apply to yohimbe as well–there’s more to good sex than an improved erection.

Steven Foster is an Herbs for Health editorial adviser and author of 101 Medicinal Herbs (Interweave Press, 1998). Additional information provided by Michael Castleman.

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