Quick answer

Ask your pharmacist or doctor before combining. NIH's two vitamin E fact sheets say vitamin E can increase the risk of bleeding in people taking anticoagulant or antiplatelet medicines, such as warfarin, because it can slow platelet clumping and work against vitamin K clotting factors. NIH says the amount needed to cause a problem is unknown.^1,2

Key facts

NIH names warfarin as the example, and its statement covers anticoagulant and antiplatelet medicines as groups.^1,2
The concern is greater when vitamin K intake is low.²
In a trial of male doctors, most of whom also took aspirin, vitamin E every other day was linked to more bleeding strokes.²
MedlinePlus asks people taking warfarin to tell their doctor and pharmacist about every vitamin and supplement they take.³

Ask your pharmacist or doctor first

Vitamin E can slow the clumping of platelets and work against the clotting factors that depend on vitamin K. Taking large doses with an anticoagulant or antiplatelet medicine, such as warfarin, can therefore increase the risk of bleeding, especially when vitamin K intake is low. NIH says the amount needed to cause a clinically significant effect is not known.^1,2

Expected from how the two work, not shown in studies

What is documented

NIH's fact sheet for consumers says vitamin E can increase the risk of bleeding in people taking anticoagulant or antiplatelet medicines, such as warfarin. Its fact sheet for health professionals explains why: vitamin E can inhibit platelet aggregation and antagonize vitamin K-dependent clotting factors, so large doses taken with these medicines can raise the risk of bleeding, especially when vitamin K intake is low.^1,2

The same fact sheet reports two trials with more hemorrhagic strokes, meaning bleeding in the brain, among people taking vitamin E. In one of them most of the men also took aspirin, which NIH says could point to a tendency of vitamin E to cause bleeding.²

Which medicines this covers

Anticoagulants such as warfarin keep blood from clotting, and antiplatelet medicines such as aspirin keep platelets from clumping. NIH's statement covers both groups but names only warfarin.^1,3,4

Newer anticoagulants such as apixaban belong to the same group. The apixaban label does not name vitamin E, but it warns that other medicines affecting clotting raise the chance of bleeding and asks people to report all vitamins and herbal supplements. Not being named is not a finding either way, so ask your pharmacist about your own medicine.⁴

How much vitamin E is involved

NIH says the amount of supplemental vitamin E needed to cause a clinically significant effect is not known. Vitamin E is in most multivitamins and in many single-ingredient supplements, so read every label, including products sold for other purposes, and show them to your pharmacist.^1,2

Signs of bleeding to report

MedlinePlus tells people taking warfarin to call their doctor about unusual bleeding, or after a fall or injury, especially to the head. Its list of warning signs includes unusual bruising, bleeding that keeps oozing from minor cuts, pink, red or dark brown urine, and red or tarry bowel movements.³

What to ask your pharmacist

Does my blood thinner interact with vitamin E?
Do any of my supplements, including my multivitamin, contain vitamin E?
Should my clotting tests be checked if I start or stop a supplement?
Does the vitamin K in my diet or supplements matter with my medicine?

MedlinePlus also asks people taking warfarin to keep the amount of vitamin K in their diet steady from week to week, which is worth raising in the same conversation.³

Questions people ask

Does the vitamin E in a multivitamin count?

NIH does not give an amount that is free of concern, and it says the amount needed to cause a problem is unknown. Show the label to your pharmacist, who knows your medicine and your dose.²

What about apixaban or other newer blood thinners?

NIH's statement covers anticoagulants as a group and names warfarin. The apixaban label does not name vitamin E, but it says that other medicines affecting clotting raise the risk of bleeding and asks people to report all vitamins and supplements. Ask your pharmacist about your own medicine.^1,4

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Sources

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.