Yohimbe (Corynanthe yohimbe) is an herb derived from the bark of the yohimbe tree found primarily in the West African nations of Cameroon, Gabon, and Zaire. The major active constituent of the bark is yohimbine. In prescription doses, the active ingredient is yohimbine hydrochloride.
Yohimbe has been used for centuries in African folk medicine to treat fevers, leprosy, coughs, and as a local anesthetic. But its most popular use has been as an aphrodisiac and a mild hallucinogen. It has been widely used in Europe for about 75 years to treat male erectile dysfunction, formerly called impotence. The U. S. Food and Drug Administration (FDA) approved yohimbe as a treatment for impotence in the late 1980s. It is sold as an over-the-counter dietary supplement and as a prescription drug under brand names such as Yocon, Aphrodyne, Erex, Yohimex, Testomar, Yohimbe, and Yovital.
There is no clear medical research that indicates exactly how or why yohimbe works in treating impotence. It is generally believed that yohimbe dilates blood vessels and stimulates blood flow to the penis, causing an erection. It also prevents blood from flowing out of the penis during an erection. It may also act on the central nervous system, specifically the lower spinal cord area where sexual signals are transmitted. Studies show it is effective in 30-40% of men with impotence. It is primarily effective in men with impotence caused by vascular, psychogenic, or diabetic problems. It usually does not work in men whose impotence is caused by organic nerve damage. In men without erectile dysfunction, yohimbe in some cases appears to increase sexual stamina and prolong erections.
Yohimbe is also used for weight loss, although not to the extent it is used for treating impotence. Some alternative health practitioners believe it is more effective and safer than the stimulant ephedra (also known as ma huang) in achieving weight loss. Yohimbe is often prescribed for weight loss by natural health practitioners at Bastyr University in Kenmore, Washington. "It's my number one choice for weight loss," Lise Alschuler, medical director of the school's natural health clinic, said in a January 1998 article in Vegetarian Times. "I prescribe it in very small doses and slowly increase intake while monitoring patients' tolerance levels." Dosing starts at 1 mg of yohimbine three times a day.
A 1994 study by the Eastern Virginia Medical School also found yohimbine may be effective in treating narcolepsy. While the study involved only eight people with the sleep disorder, seven of them given yohimbine were able to stay awake for an eight-hour work day. The researchers believe yohimbine works by counteracting the brain chemistry that causes narcolepsy, and remains effective even after a few weeks of regular use.
The usual dosage of yohimbine extract to treat erectile dysfunction is 5.4 milligrams (mg) three times a day. It may take three to six weeks for it to take effect. In the event of side effects, dosage is usually reduced to one-half a tablet three times a day, then gradually increased to one tablet three times a day. Prescription yohimbe containing yohimbine is standardized at 5.4 mg per tablet. The retail price for a name brand yohimbe is generally $18-36 for 30 tablets. A generic prescription for yohimbine is about $6-12 for 30 tablets. Most yohimbe sold over the counter is in tablet or capsule form and contains 500-1,000 mg of yohimbe bark, and contains only a small percentage of the active ingredient yohimbine. The strength of yohimbe bark extract sold over the counter varies greatly and may not be a reliable source of yohimbine. A 1995 study by the FDA looked at 26 over-the-counter yohimbe products and did not find any that
Since yohimbe can cause confusion, dizziness, and disorientation, it should not be taken while operating machinery, driving, or performing hazardous activities. It should not be taken by people with chronic health problems, such as heart, liver, or kidney disease, diabetes, glaucoma, hypertension (high blood pressure), or mental illness. Children, women, or men with prostate problems should not use yohimbe. Persons should consult their physician or health care practitioner before they start taking yohimbe.
There can be several serious side effects associated with yohimbe. An allergic reaction is possible with symptoms such as difficulty breathing, throat constriction, hives, and swelling of the face, lips, or tongue. It can also cause an irregular or rapid heartbeat, and disorientation. Minor side effects can include dizziness, anxiety, shaking, headaches, skin flushing, and irritability.
Yohimbe is also reported to have produced hallucinogenic properties in some people. The effects have been compared to the drug LSD and can last from two to four hours. These effects include audio and visual hallucinations, and feelings of euphoria. They usually occur when yohimbe is taken in higher than recommended doses.
Yohimbe should not be used by people who are taking tranquilizers, antidepressants, sedatives, antihistamines, amphetamines or other stimulants, including caffeine. Since yohimbe is a short-term monoamine oxidase (MAO) inhibitor, it should not be taken with hypertension medication. It should not be taken with food or drink that contains high amounts of tyramine, such as wine, beer, cheese, cured meats, dried fish, bananas, red plumbs, oranges, dried fruit, avocado, tomato, eggplant, and soy sauce. Doing so can cause a rise in blood pressure. Yohimbe should not be used with other prescription erectile dysfunction drugs, such as Viagra.
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Ken R. Wells
Teresa G. Odle