Viagra is very effective and fast acting -- it typically boosts blood flow within 30 minutes to several hours -- but some people prefer non-drug alternatives. Is there an alternative to Viagra, something more natural like an herb or supplement? And are any of these safe? Not every man requires the magic touch of Viagra; sometimes all one needs is a healthy diet, exercise and a little of Mother Nature s touch. Several interesting supplements have recently come to light and may provide benefits within days to weeks. Ginkgo Biloba: An herb that is commonly taken as a memory booster may provide benefits. It presumably acts by enhancing blood flow and seems relatively free of side effects. In a study conducted at the University of California, ginkgo reversed sexual problems in 84% of men who were taking antidepressant drugs such as Prozac. The ones who might benefit from it are men on Prozac or other antidepressants. The suggested dose is 80 mg three times a day, standardized to contain 24% flavone glycosides and 6% terpene lactones. Arginine: An amino acid that also enhances blood flow. In a study of 50 men at Tel Aviv University, 31% of those with impotence improved after six weeks of taking arginine. The ones who might benefit from it are men who have circulatory disorders that may be contributing to sexual problems. The suggested dose is 1 gram three times a day; sold as L-arginine. As with Viagra, you should avoid arginine if you are taking the heart medication nitroglycerin because the combination may cause a dangerous drop in blood pressure. For the same reason, you should probably not take arginine with Viagra. DHEA: This supplement may also provide benefits for men who have low levels of this hormone. DHEA helps our bodies make estrogen and testosterone, and a recent trial at the University of Vienna found it helped men with impotence. The suggested dose is 5 mg each morning for men. Yohimbe: Some studies have shown that this herb may correct impotence. However, this herb can cause a