Active constituents: The alkaloid known as yohimbine is the primary active constituent in yohimbe, although similar alkaloids may also play a role. Yohimbine blocks alpha-2 adrenergic receptors, part of the sympathetic nervous system.2 It also dilates blood vessels. Yohimbine inhibits monoamine oxidase (MAO) and therefore may theoretically be of benefit in depressive disorders. However, it does not have the clinical research of other herbs used for depression, such as St. John???s wort.
Yohimbine has been shown in double-blind trials to help treat men with erectile dysfunction.3 4 Although, negative studies have also been reported.5 6
How much is usually taken? Standardized yohimbe products are available for the treatment of erectile dysfunction. A safe daily amount of yohimbine from any product is 15???30 mg.7 Yohimbine should be used under the supervision of a physician. Traditionally, a tincture of the bark, 5???10 drops three times per day, has been used.
Are there any side effects or interactions? Patients with kidney disease, peptic ulcer or pregnant or breast-feeding women should not use yohimbe.8 Standard amounts may occasionally cause dizziness, nausea, insomnia, anxiety, increased blood pressure, and rapid heart beat,9 though all of these are rare.10 Using more than 40 mg of yohimbine per day can cause dangerous side effects, including loss of muscle function, chills, and vertigo. Some people will also experience hallucinations when taking higher amounts of yohimbine.11 Taking 200 mg yohimbine in one case led to only a brief episode of hypertension, palpitations, and anxiety.12 People with post-traumatic stress disorder13 and panic disorder14 should avoid yohimbe as it may worsen their condition.
Foods with high amounts of tyramine (such as cheese, red wine, and liver) should not be eaten while a person is taking yohimbe, as they may theoretically cause severe high blood pressure and other problems. Similarly, yohimbe should only be combined with other antidepressant drugs under the supervision of a physician, though at least one study suggests it may benefit those who are not responding to serotonin reuptake inhibitors such as fluoxetine (Prozac®).15
