The earliest mention of ginseng is in the 2,000-year-old herbal of Shen Nong:

Ginseng is most useful for maintaining good health rather than treating poor health. Can help those exposed to toxic chemicals and radiation. Has a general tonic effect on the body, in particular the adrenal glands, helping the body to withstand heat, cold, infection, other physical stresses, and radiation. Improves stamina and mental resilience, and reduces the effects of physical stress such as those endured during athletic training. Most effective in the treatment of prolonged exhaustion and debilitation resulting from over-work and long-term stress. Also stimulates immune resistance and is effective in recovery from chronic illness. Helps to prevent infection, maintains well-being, sometimes useful in treating impotence. Also a mild pain killer, and improves blood circulation. Reported to successfully treat asthma, bronchitis, cancer, flatulence, diabetes, weakness, fever, coughs and heartburn, and a mild stimulant. In tea form it helps to relieve stress and moderate heart disease.Wonderful male aphrodisiac.Continuous use leads one to longevity with light weight. Ginseng use has changed little in 2,000 years.

In the last thirty years, Asian ginseng (but not American ginseng) has been extensively studied. Like eleuthero, ginseng is an adaptogen. At least seven European clinical studies showed that standardized extracts decreased reaction time to visual and auditory stimuli; increased respiratory performance, alertness, power of concentration, and grasp of abstract concepts; and improved visual and motor coordination. Sometimes conflicting results indicate the need for further clinical studies, especially on products with well defined levels of active compounds.
Recent studies have focused on antiviral and metabolic effects, antioxidant activity, and effects on nervous and reproductive systems.
Ginseng is also a nonspecific immunostimulant similar to echinacea. There are more than eighteen active chemicals called ginsenosides in Asian ginseng. American and Asian ginsengs contain some of the same as well as some different ginsenosides which explains their different actions as expressed in traditional Chinese medicine (TCM). Mild American ginseng helps to reduce the heat of the respiratory and digestive systems, whereas the stronger Asian ginseng is a heatraising tonic for the blood and circulatory systems.

One of the problems in buying Ginseng (that it is well known among people who analyze Ginseng products) is that Ginseng products are notorious for being adultered with other drugs or chemicals. There are frequently other drugs/chemicals mixed with Ginseng products when a person buys Ginseng for consumption.

There are some significant adverse reactions associated with Ginseng. High doses of Ginseng can result in headaches. People with high blood pressure are absolutely contraindicated from taking Ginseng. Ginseng and the adulterants with it can cause abnormal vaginal bleeding and mastalgia in patients who consume it. People who take Ginseng and have estrogen-dependent malignancies (breast cancer) may need to avoid taking Ginseng, as it could increase growth rates of cancerous cells.

There are two significant drug interactions with Ginseng. Ginseng can affect platelet adhesiveness and blood coagulation. Therefore, people who are on antiplatelet therapy should be closely monitored. Ginseng also has the potential to cause hypoglycemia, which is low blood sugar, in patients with diabetes who are taking blood glucose lowering agents.

It should be noted that there is a product called Siberian Ginseng, which is chemically different than the regular Ginseng, which comes from Russia. However, all the reports about Siberian Ginseng are not from controlled studies, neither do they seem to involve any studies that are reproducible.

In Germany, Asian ginseng products may be labeled as tonics to treat fatigue, reduced work capacity, lack of concentration, and convalescence.