Science still does not know why red ginseng is effective against erectile dysfunction, only that it is.

First, don't confuse red ginseng (Panax ginseng) with other local garden varieties. Red ginseng is harvested from plants that are at least 6 years old, and is native to Asia. It is consumed as a tea or in pill form, and may also be applied as a cream.

There's been no shortage of studies into what gives red ginseng its mojo. A review of studies published in the British Journal of Clinical Pharmacology detailed how test subjects with ED fared better with red ginseng than placebo-fed control groups, but ultimately punted, concluding that larger-scale studies would be needed to understand the mechanism behind the root's success. Another study tracked 119 men with mild-to-moderate ED who were given either red ginseng or a placebo. Premature ejaculation decreased and sexual performance was enhanced for the ginseng crew, with no change in the control group – and no new insights into why the root works. The American Academy of Family Physicians reported that men who take 900 milligrams of red ginseng three time daily enjoy improved erections, but they do not vouch for enhanced sexual performance.

Some scientists believe that the answers may ultimately be found within the compounds known as gensenosides, a class of natural product steroid glycosides and triterpene saponins found almost exclusively in ginseng. Studies of these compounds have shown them to have antioxidant properties, cancer inhibiting effects, and neuro-protective protective properties of value to Alzheimer's and Parkinson's disease suffers. It is to these compounds that ginseng's other benefits – improved concentration, respiration and stamina – have been attributed.

For many men, red ginseng is their go-to supplement to address ED issues simply because it comes from the ground and not a test tube. But that's not to say that red ginseng does not have side effects of its own. Insomnia, headaches, constipation and/or an upset stomach have all been reported by men who went the “all natural” route, using red ginseng for their ED. There are insufficient data regarding any long-term effects, but neither have there been any drug interactions reported.

In no case should you take any ED medication, natural or “un,” without consulting with your doctor. One “all-natural” herbal extract marketed under the name “Ginseng Power-X” was later found to contain additives that interacted nastily with nitrates.