Quick answer

Ask your pharmacist or doctor before combining. NIH's LiverTox database lists a possible interaction between resveratrol and anticoagulant blood thinners, and the warfarin label asks for more frequent INR checks when any botanical product is started or stopped. At 1 g a day, resveratrol also slowed a liver enzyme that clears warfarin.^1,2,3

Key facts

LiverTox names anticoagulants and estrogens as possible interactions for resveratrol.¹
The warfarin label says some botanicals may add to warfarin's effect on clotting.²
The same label says drugs that slow the enzymes CYP2C9, 1A2 or 3A4 can raise warfarin's effect; at 1 g a day, resveratrol slowed CYP2C9 and CYP3A4.^2,3
The EU requires resveratrol supplement labels to say that people taking medicines should use them only under medical supervision.⁴

Ask your pharmacist or doctor first

NIH's LiverTox database lists a possible interaction between resveratrol and anticoagulant blood thinners. The warfarin label asks for more frequent INR checks whenever a botanical product is started or stopped, and MedlinePlus says some supplements may raise the risk of bleeding with warfarin.^1,2,5

Expected from how the two work, not shown in studies

What is documented

NIH's LiverTox database, which reviews medicines and supplements for liver safety, lists a possible interaction between resveratrol and anticoagulants. These are the blood thinners that slow clotting, such as warfarin.^1,5

The warfarin label does not name resveratrol. It says few studies have tested botanicals with warfarin, that some botanicals may add to its effect on clotting, and that INR should be checked more often whenever a botanical is started or stopped.²

Resveratrol extracted from plants, such as Japanese knotweed root, is a botanical product, so the label's advice on botanicals applies to it.^2,6

How it is known

Listed as a possible interaction by NIH's LiverTox database¹
Expected from how the two work: the warfarin label covers botanical products, and drugs that slow the enzymes that clear warfarin²
Reported in a study of the enzymes, not of bleeding: 1 g a day for 4 weeks slowed CYP2C9 and CYP3A4 in 42 healthy volunteers³
Not tested directly: we found no study measuring bleeding or INR in people taking resveratrol with a blood thinner

Which medicines this covers

Warfarin is an anticoagulant, and apixaban is a blood thinner that blocks a clotting factor. The MedlinePlus pages for both ask you to tell your doctor and pharmacist about vitamins, supplements and herbal products, and the apixaban page names St. John's wort, aspirin and NSAIDs as products that may interact.^5,7

Antiplatelet medicines such as aspirin and clopidogrel are also called blood thinners. The sources on this page do not name them for resveratrol. That is not a finding either way, so ask your pharmacist.

Signs of bleeding to report

MedlinePlus lists signs to report to your doctor straight away while taking these medicines. They include:^5,7

Bleeding gums or nosebleeds
Red, pink or brown urine
Red or black, tarry stools
Coughing up or vomiting blood, or material that looks like coffee grounds
Unusual bruising, or bleeding that will not stop
Headache, dizziness or weakness

What to ask your pharmacist

Should I take resveratrol at all with my blood thinner?
If I take warfarin, do I need an extra INR check when I start or stop it?
Do any of my other supplements affect bleeding or clotting?
Which signs of bleeding should make me call you?

Bring the Supplement Facts panel of every supplement you take, so your pharmacist can see how much trans-resveratrol you get each day.

Questions people ask

Can I take resveratrol with apixaban?

Ask your pharmacist or doctor first. Apixaban is a blood thinner, LiverTox names anticoagulant blood thinners for resveratrol, and the MedlinePlus apixaban page asks you to tell your doctor about herbal products.^1,7

Does the amount of resveratrol matter?

The enzyme study used 1 g a day, and lower amounts were not tested in it. Ask your pharmacist about the amount you take.³

Does this apply to aspirin?

For resveratrol, LiverTox names anticoagulants, not aspirin. Aspirin itself can interact with anticoagulants such as apixaban, so ask your pharmacist about everything you take.^1,7

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Sources

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