Clinical recommendation	Evidence rating	References	Comments
Clinicians should ask patients who take over-the-counter or prescription medications about their use of dietary supplements.	C	5, 46, 47	Many patients use dietary supplements, yet few discuss supplement use with their physicians.
Drug interactions with the following herbal supplements are unlikely or very limited: black cohosh, cranberry, ginkgo, American ginseng, milk thistle, saw palmetto, and valerian. With specific exceptions (e.g., ginkgo and warfarin [Coumadin]), clinicians should have low concern for drug interactions with these herbal supplements.	C	7–11, 13–17, 22, 24, 27–30, 41–43, 45	Numerous clinical trials report consistent findings.
Drug interactions with goldenseal and St. John's wort are highly likely, and clinicians should counsel patients to avoid concurrent use with over-the-counter or prescription medications.	C	12, 13, 15, 23, 44	Several clinical trials report consistent findings.