Effectiveness	Likely ineffective, based on preliminary evidence (small randomized controlled trials): atopic dermatitis (except perhaps for modest improvement in itch or pruritus); mastalgia; menopause; premenstrual syndrome
	Insufficient evidence: diabetic peripheral neuropathy; rheumatoid arthritis
Adverse effects	Minor gastrointestinal adverse effects, including abdominal pain, nausea, increased bowel movements, and diarrhea; headaches
Interactions	Evidence for avoiding use with phenothiazine neuroleptics or anticonvulsants is limited and anecdotal
	Evidence is also insufficient to recommend avoiding use with other drugs, including: antihypertensive agents or pressors; anticoagulants or antiplatelet agents; nonsteroidal anti-inflammatory drugs; herbs or supplements that might affect platelet aggregation
Dose	Varies depending on brand; available in capsule and liquid form
Cost	$11 to $48 for a four-week supply, depending on brand and dosage
Bottom line	Widely used with little proven effectiveness, but safe when used in recommended doses for up to six months