Warfarin interaction2

DECREASE
Taken from:
PHARMACEUTICAL SERVICES DIVISION, MINISTRY OF HEALTH, MALAYSIA. Medication Therapy
Adherence Clinic: Warfarin Protocol. 1 st ed. Malaysia: Pharmaceutical Services Division, 2010.

No. Food Possible MOA Potential Effect
Towards INR
1. Cranberry Juice Inhibitor of CYP enzyme
2. Garlic Intrinsic antiplatelet activity
3. Chitosan Impairment of absorption of
vitamin A, D, E, K
4. Kale (Cooked) 531 mcg of Vit K in ½
cup
5. Spinach (Cooked) 444 mcg of Vit K in
½ cup
6. Mustards green (Raw) 279 mcg of Vit
K in 1 cup
7. Parsley (Raw) 246 mcg of Vit K in ¼
cup
8. Brussels sprouts (Cooked) 219 mcg of
Vit K in 1 cup
9. Spinach (Raw) 145 mcg of Vit K in 1
cup
10. Broccoli (Raw) 89 mcg of Vit K in 1
cup
11. Cabbage (Cooked) 82 mcg of Vit K in
½ cup
12. Kailan (Cooked) 74.62 mcg of Vit K in
1 cup
Supplementation of vitamin K
Supplementation of vitamin K
Supplementation of vitamin K
Supplementation of vitamin K
Supplementation of vitamin K
Supplementation of vitamin K
Supplementation of vitamin K
Supplementation of vitamin K
Supplementation of vitamin K
13. Alcohol Chronic alcohol intake
Can induce warfarin metabolism
by cytochrome P450 and increase
warfarin clearance
Acute alcohol intake
Warfarin metabolism may be
decreased, leading to
supratherapeutic INR
14. Soy Speculative mechanisms of soy
milk-induced INR decline such as
changes in warfarin absorption or
metabolism resulting from
alterations in P-glycoprotein
efflux system or organic aniontransporting
polypeptides

No. Food Possible MOA Potential Effect
Towards INR
15. Mango Retinol (vitamin A) inhibits
CYPC219 (which warfarin R
isomer)
16. Curcumin Inhibition P-gp, further improving
adsorption of warfarin
17. Pineapple Inhibition of CYPC29 (due to
bromelain)
18. Mangosteen Inhibition of CYP2C9
19. Pomegranate Inhibit metabolism involving the
cytochrome P450 system
20. Ginger Reduced platelet aggregation
Unquantifiable

No. Supplements Possible MOA Potential Effect
Towards INR
1. Chlorella Contains large amount of vitamin
K
2. Chondroitin Inhibit activated factor X
3. Coenzyme Q10 Structurally related to
menaquinone (Vitamin K2)
4. Cranberry juice Contains flavonoids which may
alter metabolism of warfarin
5. Evening primrose oil Inhibit platelet aggregation
6. Fish oil supplement Omega-3 fatty acids may affect
platelet aggregation and/or
vitamin K-dependant coagulation
factors
7. Flaxseed oil Reduced platelet aggregation
8. Blackseed oil (Habbatus sauda) Unknown
9. Garlic Reduced platelet aggregation
10. Ginkgo Reduced platelet aggregation
11. Glucosamine Unknown
12. Grape seed supplement Contains tocopherol (one form of
vitamin E)
13. Minerals (Iron, magnesium and zinc) Iron, magnesium and zinc may
bind with warfarin, potentially
decreasing their absorption and
activity
14. Papain (papaya enzyme) Papain may damage mucous
membranes of the GI tract,
leading to increased risk of
bleeding
15. Probiotics Increase production of intestinal
vitamin K
16. Pumpkin seed Unknown. Usually when taken in
combination with saw palmetto
and vitamin E

No. Food Possible MOA Potential Effect
Towards INR
17. Royal jelly Unknown
18. Safflower oil Inhibit platelet aggregation
19. Saw palmetto Inhibit cyclooxygenase and
CYPC29
20. Vitamin A (>25000IU/day) Unknown
21. Vitamin B3 (Niacin) Additive anticoagulant effect and
decreased CYP450-mediated
metabolism of warfarin
22. Vitamin C (>1g/day) Unknown
23. Vitamin E (>400 units/day) Pharmacodynamic synergism.
Inhibition the oxidation of
reduced vitamin K, which is
necessary for carboxylation of
vitamin K-dependant clotting
factors for these clotting factors
to be fully functional
24. Vitamin K Antagonised effect of warfarin

No. Herbal Possible MOA Potential Effect
Towards INR
1. Aloe vera When taken orally, aloe latex is a
type of laxative called stimulant
laxative. Stimulant laxatives
speed up the bowels and can
cause diarrhea in some people.
Diarrhea can increase the effects
of warfarin and increase the risk
of bleeding
2. Arnica Contains coumarin derivatives
3. Anise (Bunga lawang) Contains coumarin derivatives
4. Black tea Reduces warfarin effect and
increase the risk of clotting. It iis
unclear why this interaction
might occur
5. Celery Contains coumarin derivatives,
which may possibly potentiate
effect of warfarin
6. Chamomile Contains coumarin derivatives,
which may possibly potentiate
effect of warfarin
7. Clove (Bunga Cengkih) Exhibit antiplatelet activity
8. Danshen Increased INR and prolonged
PT/PTT (i.e. altered
pharmacokinetics) by reducing
elimination of warfarin, reduced
platelet aggregation and TXA
formation)
9. Fenugreek (Halba) May contain coumarin
derivatives
10. Gamat Contains chondroitin
11. Ginseng, American Induced CYP450 enzyme system
activity and increased warfarin
elimination
12. Ginseng, Oriental Unknown
13. Ginseng, Siberian Unknown
14. Goji berry Unknown

No. Food Possible MOA Potential Effect
Towards INR
15. King of bitter (Hempedu bumi) Its active chemical,
Andrographolide, possessed
antithrombotic activity via
inhibition of platelet aggregation
16. Kacip Fatimah Inhibit CYPC28, C29, 2C19
activities
17. Lotus seed Inhibit platelet aggregation and
thrombus formulation
18. Parsley May contain warfarin derivatives
19. Senna Causes diarrhea, resulting in
increased effect of warfarin
20. Sky fruit (Buah tunjuk langit) Inhibit platelet-activating factor
(PAF) and PAF-induced platelet
aggregation
21. St. John’s Wort Induced CYP2C9 and leads to
increase metabolism of warfarin
22. Tongkat Ali Contains major components of
quassia which may increase the
risk of bleeding when taken with
drugs that increase the risk of
bleeding
23. Turmeric Inhibit platelet aggregation
24. Wintergreen Contains methyl salicylate
Modified from:
MALAYSIAN PHARMACEUTICAL SOCIETY, Warfarin Interaction Handbook. 1 st ed. Selangor: Malaysian
Pharmaceutical Society, 2017