Interactions of warfarin with garlic, ginger, ginkgo, or ginseng: nature of the evidence.
OBJECTIVE
To review and characterize the evidence describing potential interactions between warfarin and garlic, ginger, ginkgo, or ginseng.


METHODS
Searches of MEDLINE (1966-1999), other bibliographic databases, several abstracting services, and tertiary references were conducted.


METHODS
Articles were examined by each author, and additional citations were obtained from the references of these articles. Preference was given to Englishlanguage articles of human studies.


RESULTS
Evidence is lacking for an interaction of warfarin wth galic or ginger. One case report associates ginseng use with decreased warfarin-maintained anticoagulation effect. Another case report links concomitant use of ginkgo and warfarin with the development of intracerebral hemorrhage. Hemorrhage and tendencies were noted in four cases with ginkgo use and in three cases with garlic; in none of these cases were patients receiving warfarin.


CONCLUSIONS
The true risks of these interactions and effects are difficult to characterize due to the limited number and nature of existing reports.
Vaes
L P
LP
Faculty of Pharmacy, The University of Utrecht, The Netherlands.
Chyka
P A
PA
D000925:Anticoagulants / Q000494:pharmacology; D019587:Dietary Supplements; D004347:Drug Interactions; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D005737:Garlic / Q000737:chemistry; D020939:Zingiber officinale / Q000737:chemistry; D020441:Ginkgo biloba / Q000737:chemistry; D041743:Herb-Drug Interactions; D006801:Humans; D005894:Panax / Q000737:chemistry; D010936:Plant Extracts / Q000494:pharmacology; D010946:Plants, Medicinal; D014859:Warfarin / Q000494:pharmacology*
D000925:Anticoagulants; D004365:Drugs, Chinese Herbal; D010936:Plant Extracts; D014859:Warfarin