Asiatic ginseng, Panax schinseng, and the American wild ginseng, Panax quinquefolius, are closely related and similar in both appearance and effects. Siberian ginseng includes species of a different family, the Eleutherococcus family, which is not real ginseng.
There is not a big medicinal difference between the two “real” ginsengs. Each has a slightly different composition of ginsenosides, active ingredients that can be either stimulants or the opposite; American ginseng is slightly less stimulating than Asiatic ginseng.
The principal use of ginseng is to make people feel better, and there is evidence that it works, especially in older people. Its reputation in ancient Chinese medicine as an aphrodisiac is not scientifically proven.
Prepared ginseng root should be bought from a reputable source.
Side effects can result from adulterants used to extend an expensive product. Makers offer different concentrations, from about 4 to 7 percent, so follow the dosage on the label.