Ginkgo Biloba and Blood Thinners: What You Need to Know Before Taking Both

If you're taking a blood thinner like warfarin, aspirin, or clopidogrel, and you're thinking about adding Ginkgo biloba for memory or circulation, stop. Not because it's definitely dangerous-but because you need to talk to your doctor first. This isn't a simple yes-or-no question. It's a balancing act between what's proven, what's suspected, and what's just plain confusing.

What Is Ginkgo Biloba, Really?

Ginkgo biloba comes from the leaves of the Ginkgo tree-one of the oldest living tree species on Earth, unchanged for over 270 million years. It's been used in traditional Chinese medicine for centuries, but the version sold in the U.S. and Europe today is a highly processed extract, usually labeled as EGb 761. This isn't just dried leaves in a capsule. It's a standardized mix of 24% flavonol glycosides and 6% terpene lactones, designed to be consistent from bottle to bottle. About 70% of global Ginkgo supplements are this exact formula. It's not a herbal tea you brew at home. It's a pharmaceutical-grade extract.

People take it for memory, brain fog, or poor circulation. Around 12 million Americans use it every year. But here's the problem: if you're on a blood thinner, mixing the two might not be worth the risk-even if the science isn't 100% clear.

How Ginkgo Might Affect Blood Thinning

Ginkgo doesn't work like warfarin or aspirin. It doesn't directly thin your blood. Instead, it interferes with platelets-the tiny cells in your blood that clump together to form clots. Research shows it can block signals that tell platelets to stick together. In theory, that means your blood takes longer to clot. That’s the same effect you get from aspirin or clopidogrel, just through a different path.

There's also evidence Ginkgo might affect how your liver processes certain blood thinners, especially warfarin. It could slow down the breakdown of S-warfarin, making it stick around longer in your system. That’s not a guess-it's been shown in lab studies. But here's where it gets messy: in controlled trials with healthy volunteers, this effect often doesn't show up. Or if it does, it's too small to matter.

So why do people end up in the ER with brain bleeds after taking Ginkgo and warfarin? Because those cases usually involve non-standardized products-cheap supplements with inconsistent doses, or ones that contain unknown contaminants. The studies that found no risk? They used EGb 761. The case reports? They didn't.

What the Experts Say-And Why They Disagree

You'll find conflicting advice everywhere. The Mayo Clinic says Ginkgo "may raise your risk of bleeding" with blood thinners. GoodRx calls warfarin a "high-risk" combo and says to avoid it entirely. The Cleveland Clinic lists blood thinners as a clear contraindication.

But then you read the 2008 review in PubMed, which analyzed 17 clinical trials and concluded: "There is scant information to support the suggestion that Ginkgo potentiates the effects of anticoagulant or antiplatelet drugs." The American Society of Health-System Pharmacists calls the risk "theoretical." The American College of Chest Physicians says routine discontinuation isn't needed.

Why the split? Because the evidence is split. Controlled trials-where people are carefully monitored, given precise doses, and followed over time-show little to no interaction. But real life isn't a trial. People take different brands. They take other herbs. They skip doses. They don't tell their doctors. And when something goes wrong, it's often hard to prove Ginkgo was the cause.

Which Blood Thinners Are Most Concerning?

Not all blood thinners are the same. Here’s how Ginkgo interacts with the most common ones:

• Warfarin (Coumadin, Jantoven): This is the biggest red flag. Even though clinical trials don't show a strong interaction, case reports of serious bleeding-including brain hemorrhages-are linked to Ginkgo + warfarin. The FDA received 18 reports of possible bleeding events tied to Ginkgo between 2008 and 2020. Causality wasn't proven, but the pattern is enough to make doctors nervous.
• Aspirin: One major study found no increase in bleeding when Ginkgo was added to low-dose aspirin. But other reports say otherwise. The risk here is considered moderate, not high.
• Clopidogrel (Plavix): A 2020 study found Ginkgo was involved in 2.6% of clopidogrel prescriptions. That might sound low, but it's still higher than most herbal interactions. Platelet inhibition from both could be additive.
• DOACs (Apixaban, Rivaroxaban, Dabigatran): These newer drugs have less known interaction data. But 18% of cases in one study showed Ginkgo use alongside DOACs. Since these drugs are metabolized differently than warfarin, the risk profile might be different-but we just don't know enough yet.

And it's not just prescription drugs. Ginkgo also interacts with garlic, danshen, and evening primrose oil-all of which can affect bleeding. So if you're taking three herbal supplements and one blood thinner, you're stacking risks.

What Should You Do?

There's no one-size-fits-all answer. But here’s what the most reliable sources agree on:

1. Don't start Ginkgo without telling your doctor. Especially if you're on any blood thinner. Even if you've been taking it for years, mention it at your next appointment.
2. If you're scheduled for surgery, stop Ginkgo. The American Society of Anesthesiologists recommends stopping herbal supplements at least two weeks before any procedure. That includes Ginkgo. Some experts say 36 hours is enough. But if you're on warfarin, two weeks is the safe bet.
3. Check your supplement label. About 42% of Ginkgo products now warn about blood thinners. If yours doesn't, that's a red flag. It might not be a quality product.
4. Track your INR if you're on warfarin. Your doctor should check your blood clotting time regularly. If your INR suddenly climbs without a change in diet or medication, Ginkgo could be the culprit.
5. Don't assume "natural" means safe. Ginkgo is a powerful plant extract. It's not harmless. Just because it's sold in a health food store doesn't mean it's risk-free.

What About Pharmacists?

You'd think pharmacists would be the first line of defense. And they are. A 2022 survey found that 78% of pharmacists routinely warn patients about Ginkgo-blood thinner interactions. Sixty-three percent recommend stopping it before surgery. That's more than most doctors do.

Electronic health records now flag these combinations too. Epic's system alerts doctors when Ginkgo is prescribed with warfarin. Cerner flags it with any anticoagulant. These aren't perfect systems-they generate false alarms-but they're there because the risk, however small, is real enough to warrant a warning.

Bottom Line: Play It Safe

The science is murky. Some studies say Ginkgo is fine with blood thinners. Others say it's a ticking time bomb. The truth? We don't know for sure. But we do know this: bleeding in the brain, stomach, or eyes doesn't come with a warning label. And once it happens, you can't undo it.

If you're taking a blood thinner and thinking about Ginkgo, the safest choice is simple: don't take it. If you're already taking it, don't quit cold turkey without talking to your doctor. But do talk. Bring the bottle. Show the label. Ask: "Could this be affecting my blood thinning?"

There's no magic pill for memory or circulation that's worth risking a stroke or internal bleeding. Your health isn't a gamble. Don't let a supplement turn your treatment plan into a coin toss.