http://www.medicinenet.com/script/main/art.asp?ArticleKey=7506&page=2
Ginseng can cause elevation in blood pressure, headache, vomiting, insomnia,
and nose bleeding. Ginseng can also cause falsely abnormal blood tests for
digoxin level in persons taking the drug for heart disease. It is unclear
whether ginseng may affect female hormones. Its use in pregnancy is not
recommended.

Ginseng may affect the action of the normal blood clotting element
(platelets). It should be avoided in patients taking aspirin, nonsteroidal
antiinflammatory drugs (such as ibuprofen (Advil), naproxen (Aleve) or
Motrin), or medications to prevent blood clotting (anticoagulants) such as
warfarin (Coumadin).

Ginseng may also cause headaches, tremors, nervousness, and sleeplessness.
It should be avoided in persons with manic disorder and psychosis.