Yohimbe has been used in West Africa for centuries as an aphrodisiac and treatment for sexual dysfunction. The bark of this tall evergreen tree contains over 30 different alkaloids, some of which are sedatives or tranquilizers, and others that mimic the stimulant neurochemical norepinephrine. The most potent of these is the alkaloid yohimbine, which has been used as a pharmaceutical treatment for impotence in the United States since 1938. While yohimbine has largely been supplanted by Viagra and other drugs for the treatment of erectile dysfunction, it is still occasionally recommended as a treatment for psychogenic impotence. Due to the high incidence of side effects and drug interactions accompanying the use of yohimbe alkaloids, it is important to consult with a doctor before taking yohimbe.
Norepinephrine Levels
In a study by the University of Washington School of Medicine, researchers found that the alkaloid yohimbine exerts some of its central nervous system stimulating effects by increasing serum levels of the neurotransmitter norepinephrine. According to the University of Maryland Medical Center, norepinephrine both affects nerve cells directly and travels throughout your body controlling the actions of cells and organs. Produced in the adrenal glands, norepinephrine is sometimes called the stress hormone, as it produces tension, excitation and elevated blood pressure levels.
Pharmacodynamics
It is believed that yohimbine raises serum norepinephrine levels by activating presynaptic alpha 2-adrenergic receptors in your central nervous system. Since norepinephrine receptors act as their own negative feedback mechanism, inhibiting the release of more norepinephrine as serum levels increase, yohimbine binding to these sites promotes the release of larger amounts of norepinephrine. This process is known as norepinephrine spillover, and results in central and autonomic nervous system stimulation.
Potential Side Effects
The increased genital sensitivity initiated by yohimbe is believed to be produced by yohimbine's effects on serum norepinephrine levels. Yohimbine's affinity for neurons in the sacral region may cause an increase in your reflex excitability, decreasing the time needed for orgasm. This localized nerve stimulation produced by increased norepinephrine release may also produce cold, tingling or pins-and-needles sensations in the lower back and spine, as well as an increased intensity of orgasm.
Drug Interactions
The central nervous system stimulating properties of yohimbe and yohimbine-containing products can cause toxic side effects when combined with other stimulants. According to the Mayo Clinic, both bupropion and methamphetamine are known to interact negatively with yohimbe. Mixing stimulants can exacerbate their potential to cause elevated heart rate, anxiety and hypertension. The elevated levels of norepinephrine produced by yohimbe have the potential to affect child development, and should not be consumed by women who are pregnant or breast-feeding. The risk for elevated blood pressure is of particular concern if you have kidney disease, as high doses may cause kidney failure. Common side effects also include headache, anxiety, dizziness, nausea, loss of appetite, vomiting, tremors and sleeplessness.
References
- National Center for Complementary and Alternative Medicine; Yohimbe; July 2010
- Memorial Sloan-Kettering Cancer Center; Yohimbe; March 2011
- National Toxicology Program Study Reports; Yohimbe Bark Extract / Yohimbine; November 1999
- Mayo Clinic; Erectile Dysfunction Herbs: A Natural Treatment for ED?; Mayo Clinic staff; September 2010
- University of Maryland Medical Center; Impotence (Erectile Dysfunction)
- "Neuroendocrinology"; Yohimbine Increases Cerebrospinal Fluid and Plasma Norepinephrine but Not Arginine Vasopressin in Humans; Elaine R. Peskind, et al; March 1989
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