Many generations of people in West Africa have employed the bark of the Pausinystalia yohimbe tree as an aphrodesiac and treatment for male sexual dysfunction. While yohimbine HCl, a compound isolated from the bark, has been used as a drug to treat impotence since 1938, modern medications are safer and more effective for most people. Extracts of the bark, however, are still widely used in alternative medicine despite the risk of side-effects.
Adrenergic Activity
The alkaloid yohimbine alone appears to exert some of its central nervous system, or CNS, stimulating effects by increasing the body's own stimulant hormone adrenaline, or epinephrine. It accomplishes this by interfering with the body's adrenaline regulatory feedback systems. Adrenaline, manufactured by the adrenal glands, may produce stress, tension, and excitation as its levels increase in the bloodstream. According to the University of Maryland Medical Center, adrenaline affects the activity of organs and cells directly, in addition to its central nervous system stimulating properties.
Mechanism of Action
Yohimbine's elevation of serum adrenaline levels may be partially responsible for its effects on male sexual arousal. Since the chemical blocks presynaptic a2-adrenergic receptors in the brain that adrenaline would normally bind to, the body underestimates the amount present in the blood. This process is called adrenaline spillover, and can cause elevated heart rate, blood pressure, respiration, and anxiety in addition to sexual arousal, according to the Memorial Sloan-Kettering Cancer Center.
Side-Effects
Yohimbe's adrenaline-like activity can cause several common side-effects, including sensations of cold, chills, tingling or pins-and-needles across the lower back and spine, as well as increased intensity of orgasm. These sensations are produced by yohimbine HCl's direct stimulation of neurons in the sacral region, particularly those in the sacral and coccygeal nerve trunks. Yohimbine HCl's action on nerves in the pelvic region may also increase reflex excitability, dramatically decreasing the time required to achieve orgasm. This may prove problematic for men with other types of sexual dysfunction, such as premature ejaculation. Other side-effects include headache, insomnia, nausea, elevated heart rate, hypertension, restlessness and anxiety, according to MayoClinic.com.
Drug Interactions and Contraindications
If you are considering taking yohimbe, it is important that you first consult with your doctor. Yohimbe is a potent stimulant and can produce toxic reactions when combined with other stimulants. According to MayoClinic.com, the stimulant antidepressant Wellbutrin and the ADHD drug Adderall should not be combined with yohimbe. Doing so may magnify the potential for a racing heart, anxiety and high blood pressure. Due to its effects on blood pressure, yohimbe should not be taken by people at risk of heart attack or stroke, or who have been diagnosed with kidney disease.
References
- "Neuroendocrinology"; Yohimbine Increases Cerebrospinal Fluid and Plasma Norepinephrine but Not Arginine Vasopressin in Humans; Elaine R. Peskind, et al; March 1989
- "Journal of Clinical Pharmacology"; Manipulation of Norepinephrine Metabolism with Yohimbine
- University of Maryland Medical Center; Dictionary of Cancer Terms: Norepinephrine
- 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
- National Center for Complementary and Alternative Medicine; Yohimbe; July 2010
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