St. John's wort, Panax ginseng and green tea supplements are among those that can produce potentially dangerous interactions with chemotherapy, according to the study.

Panax, pa-naks′, n. a genus of shrubs with radiately or pinnately compound leaves and small flowers in compound umbels, the ginseng.

Other roots are substituted for it, notably that of Panax quinquefolium, distinguished as American ginseng, and imported from the United States.