Herb	Use	Dosage		Comments
Echinacea	Immune stimulation	No well-controlled studies define dosing		Human and animal studies: increases phagocytosis, lymphocytic activity, cellular respiration and activity against tumor cells; no bactericidal and bacteriostatic properties; probably should not be taken for more than 8 successive weeks; no documented side effects, drug interactions or toxicity
		Traditional dosing:
			Maximum daily dosage in adults: 6 to 9 mL of expressed fresh juice, or 1.5 to 7.5 mL of tincture or 2 to 5 g of dried root
Feverfew	Migraine headache prophylaxis	125 mg daily of standardized extract (standardized to 0.2% Parthenolide)		[ corrected] Inhibits prostaglandin production; serotonin antagonist; not recommended in pregnancy; induces menstruation; caution with anticoagulants; no documented problems
Garlic	Atherosclerosis	No well-controlled studes define dosing		Inhibits platelet function; increases serum insulin levels and improves glycogen storage; concerns about increased postoperative bleeding
		Traditional dosing:
			4 to 12 mg of allicin, or 0.4 to 12 g of dried powder or 2 to 5 g of fresh bulb daily
Ginkgo biloba	Mild to moderatecerebral insufficiency; favorable for PMS and vertigo	120 to 160 mg daily of standardized extract (standardized to 24% flavone glycosides and 6% terpene lactones)		Complaints of transient headache; no documented severe side effects (one case report of spontaneous subdural hematoma in a healthy adult); caution with concurrent use of aspirin and NSAIDs
	Dementia	120 mg daily of standardized extract, as above
St. John's wort	Mild to moderate depression	300 mg three times daily or 450 mg twice daily of standardized extract (standardized to 0.13 to 0.30% hypericin)		Inhibits uptake of neurotransmitters serotonin, norepinephrine and dopamine, and binds to GABA receptors in vitro; MAOI activity in vitro, not in vivo; no major side effects—minor complaints of dry mouth, dizziness, constipation and confusion; photosensitivity with high dosages (600 mg three times daily of 0.24 to 0.32% hypericin); uterotonic in animals in pregnancy; no known drug interactions, but because of neurotransmitter activity, exercise caution if used with other antidepressants
		Maximum in studies: 1,000 mg daily