Because panax ginseng has a stimulating effect, some experts caution against using it for longer than three weeks at a time, or using it at all if you have high blood pressure or consume a lot of caffeine. Ask your doctor Yohimbe bark, taken from a towering evergreen tree, was traditionally used in its native Africa to stimulate erections. A century before Viagra, yohimbine, a substance derived from the bark, was prescribed in Europe for male sexual dysfunction. A combined analysis of more than a dozen studies involving hundreds of subjects, published in the journal Archives of Sexual Behavior in August 1996, concluded that yohimbine can help many men who have problems getting an erection. It appears to work in part by increasing blood flow to the penis and may affect brain chemistry as well.
Research results on yohimbine in women, on the other hand, are mixed.
And there's not much evidence that it will charge up the appetite of an already healthy man. As for the yohimbe available over the counter, a 1995 analysis of 19 such products found that most products examined contained almost no measurable yohimbine. Things may have changed since then, but if you're going this route, your best bet is to ask your doctor whether a prescription is right for you. Both effects could be caused by ginkgo's encouragement of increased peripheral blood flow, says Blumenthal. After a geriatric patient taking the extract for memory protection reported improved erections, researchers at the University of California at San Francisco put it to the test.