Table 3: Summary of herb-warfarin interactions supported by clinical evidence.

Herbs
(common and Latin name)
Clinical effectsSeverityReliabilities of evidenceMechanisms
PKPD

Cranberry
(Vaccinium macrocarpon)
PotentiationMajor [55]IF [52, 53, 160]D [40]
Soya
(Glycine max Merr.)
InhibitionModerate [115, 116]IF [113, 114]B [115]
St John’s wort
(Hypericum perforatum)
InhibitionMajor [121, 122]IF [41, 118, 119]NA
Danshen
(Salvia miltiorrhiza)
InhibitionModerate [133, 134]IF, G [131, 132, 135, 136]A,C [40]

Coenzyme Q10
(Theobroma cacao)
InhibitionMinor [47, 48]IINAB [50]
Chinese angelica
(Angelica sinensis)
PotentiationModerate [126]IIF [125]C [40]
Ginger
(Zingiber officinale Roscoe)
PotentiationModerate [161]IINAA [162]

Chamomile
(Matricaria recutita)
PotentiationMajor [44]IIIF [41, 163, 164]NA
Chitosan
(Swertia chirayita)
PotentiationModerate [46]IIINAB [45]
Cannabis
(Cannabis sativa L)
PotentiationMajor [165]IIIF [166]NA
Devil’s claw
(Harpagophytum procumbens)
PotentiationModerate [61]IIIF [60]NA
Ginkgo
(Ginkgo biloba)
PotentiationMajor [83]IIIF [7577]NA
Garlic
(Allium sativum)
PotentiationMajor [40]IIIF [167, 168]A [73, 169]
Ginseng
(Panax quinquefolius/Panax ginseng)
InhibitionModerate [170]IIIF [40]A [87]
Grapefruit
(Citrus paradise)
PotentiationMajor [94]IIIF [95]NA
Green tea
(Camellia sinensis)
InhibitionModerate [97]IIINAB [99]
Lycium
(Lycium barbarum)
PotentiationMajor [139]IIIF [137]NA

Boldo
(Peumus boldus)
PotentiationMinor [36]IVNAC [40]
Echinacea
(Echinacea purpurea)
InhibitionMinor [66]IVF [119, 171]NA
Fenugreek
(Trigonella foenum-graecum)
PotentiationMinor [36]IVNAB, C [40]
Melilot
(Melilotus officinalis)
PotentiationModerate [102]IVNAC [40]
Parsley
(Petroselinum crispum)
PotentiationModerate [104]IVF [103]B [40]
Pumpkin
(Cucurbita pepo)
PotentiationMinor [106]IVNAB [40]
Red clover
(Trifolium pretense)
PotentiationMajor [108]IVF [60, 107]NA
Saw palmetto
(Serenoa repens)
PotentiationMinor [106, 111]IVF [109]NA

Notes. (1) As to mechanisms of herb-warfarin interaction, PD factors including the following: A: interference with platelet function; B: altering gut vitamin K synthesis or containing vitamin K; C: interference with vitamin K cycle; D: interference with coagulation cascade. PK factors including the following: E: interference with warfarin absorption; F: interference with metabolizing enzymes of warfarin; G: interference with protein binding of warfarin. (2) Other nonclinical evidenced herbs defined as doubtful in Section 3 were excluded in this table.