Potential risks of health food products containing yohimbe extractsBMJ 1994; 309 doi: https://doi.org/10.1136/bmj.309.6959.958 (Published 08 October 1994) Cite this as: BMJ 1994;309:958
- P A G M De Smet,
- O S N M Smeets
EDITOR, - We wish to express our concern about the availability of yohimbe preparations on the health food market. We submitted capsules that contained yohimbe extracts (imported from France by Nutramin, Amsterdam) to thin layer chromatography and high performance liquid chromatography and recovered, besides several other alkaloids, at least l mg of yohimbine per capsule. The recommended daily dose of 8-10 capsules would therefore provide at least 8-10 mg of yohimbine a day, and the other alkaloids might also contribute to the effect.
The label describes the product as a vitalising agent for men, but off label advertising advocates the product for the treatment of male impotence. While yohimbine has shown favourable results in this condition, it is not universally accepted as an effective aphrodisiac and is not sufficiently safe to be freely available for uncontrolled use. When given to healthy volunteers 15-20 mg of yohimbine orally is usually needed to increase blood pressure and to induce anxiety, but in patients taking tricyclic antidepressants hypertension may occur at 4 mg three times a day, and the toxicity of yohimbine can be enhanced by other drugs, such as phenothiazines.1 A dose of 5 mg is sufficient to produce adverse effects in patients with autonomic failure,2 and 10 mg can elicit manic-like symptoms in patients with bipolar depression.3 Furthermore, daily doses of 15 mg have been associated with bronchospasm4 and a lupus-like syndrome.5
The label of the capsules that we investigated does not provide any warning about such health risks, and off label advertising presents yohimbine merely as a peripheral vasodilator which can potentiate other agents that lower blood pressure. In reality, however, the alpha2 adrenoreceptor antagonistic properties of the alkaloid reverse the effects of clonidine and similar antihypertensive drugs.
In view of these data, we have requested the Dutch department of health to take steps against the uncontrolled availability of health food products containing yohimbe extracts, and we hope that authorities in other countries will also take action. Doctors should also be aware that such preparations may not have the composition that is declared on the label. When we analysed a second product on the Dutch market (imported from the United States by Body Food, Ridderkerk) it yielded only caffeine and no yohimbine, even though the label claimed that 500 mg of yohimbe bark extract was present in each tablet.