Ginkgo Biloba and Blood Thinner Interactions: What You Need to Know

More than 12 million Americans take Ginkgo biloba supplements every year, mostly for memory or circulation. But if you're on a blood thinner-whether it's warfarin, aspirin, clopidogrel, or one of the newer DOACs like apixaban-you need to pause and think before taking it. The problem isn't just about one herb. It's about what happens when something natural meets powerful medicine.

What Is Ginkgo Biloba, Really?

Ginkgo biloba comes from the leaves of a tree that’s been around for over 270 million years. It’s one of the oldest living tree species on Earth. The extract used in supplements is standardized as EGb 761, which means it has a consistent mix of active compounds: 24% flavonol glycosides and 6% terpene lactones. This specific blend makes up about 70% of all Ginkgo products sold globally.

It’s not just a trendy supplement. It’s been used in Chinese medicine for centuries and entered Western medicine in the 1950s. Today, the global market for Ginkgo is worth nearly $2 billion, and it’s growing. But here’s the catch: most of the research on its safety comes from studies using this exact standardized extract. Many store-bought supplements aren’t made the same way.

How Ginkgo Might Affect Blood Thinning

Ginkgo doesn’t work like warfarin or aspirin. It doesn’t directly thin your blood. Instead, it affects platelets-the tiny cells in your blood that clump together to form clots. Research shows Ginkgo can block signals that make platelets sticky. That’s why some scientists think it might increase bleeding risk.

It also interacts with liver enzymes, especially CYP2C9, which is how your body breaks down warfarin. If Ginkgo slows that process down, warfarin sticks around longer. That could make your blood too thin. That’s the theory.

But here’s where it gets messy. In controlled clinical trials, researchers gave people Ginkgo along with aspirin or warfarin and found no major increase in bleeding. One study even showed no change in clotting times. So why do doctors still warn about it?

The Case Reports That Changed Everything

While lab studies say Ginkgo is safe, real-life stories don’t. Between 2008 and 2020, the FDA received 18 reports of bleeding events linked to Ginkgo use. These weren’t just nosebleeds. They included brain bleeds, internal bleeding after surgery, and unexplained bruising. In nearly every case, the person was also taking a blood thinner.

The problem? Most of these cases involved non-standardized Ginkgo products. Some had unknown doses. Others were contaminated. One study found that 21% of patients taking blood thinners were also using herbal supplements like Ginkgo-and almost half of them were at risk for dangerous interactions.

That’s why the Mayo Clinic and GoodRx say: avoid Ginkgo if you’re on warfarin. They call it a "high-risk" interaction. The Cleveland Clinic lists blood thinners as a direct contraindication. But the American Society of Health-System Pharmacists says the risk is "theoretical." What gives?

Why Experts Disagree

The divide comes down to evidence type. Controlled studies? Mostly safe. Case reports? Often dangerous. The difference? Quality.

Studies using EGb 761-the gold-standard extract-show little to no interaction. But the supplements you buy at the grocery store? They might not even contain that extract. Some have less than half the active ingredients. Others have contaminants that affect clotting. A 2023 survey found that 42% of Ginkgo labels now warn about blood thinners-up from 28% in 2018. That’s because manufacturers are seeing the same case reports you are.

Dr. Michael Murray recommends stopping Ginkgo 36 hours before surgery. Dr. Tieraona Low Dog says two weeks. The American Society of Anesthesiologists agrees with the two-week rule. But the American College of Chest Physicians says there’s no proof you need to stop it at all. So which do you follow?

What the Data Says About Specific Blood Thinners

Not all blood thinners react the same way with Ginkgo. Here’s what the numbers show:

Warfarin is the biggest red flag. The PLOS ONE study found that 18% of patients on DOACs who also took Ginkgo had a documented interaction. That’s a lot. And while aspirin seems safer in trials, real-world cases show increased bruising and bleeding, especially in older adults.

What Should You Do?

If you’re on a blood thinner and thinking about taking Ginkgo, here’s what to do:

1. Stop. Don’t start. If you’re not already taking it, don’t begin unless your doctor says it’s safe.
2. Check your current supplements. Look at your bottle. Does it say "EGb 761"? If not, you don’t know what you’re getting.
3. Talk to your pharmacist. They see your full medication list. They’ll know if Ginkgo could clash with anything else you take.
4. Stop Ginkgo before surgery. Whether it’s a dental extraction or knee replacement, stop it at least two weeks before. That’s the safest window.
5. Watch for signs of bleeding. Unexplained bruising, nosebleeds that won’t stop, dark stools, or headaches could mean your blood is too thin.

And if you’re already taking Ginkgo? Don’t quit cold turkey. Talk to your doctor. Suddenly stopping could affect your circulation. But don’t keep taking it blindly either.

What About Other Herbs?

Ginkgo isn’t alone. Garlic, danshen, evening primrose, ginger, and turmeric also affect platelets. If you’re on a blood thinner, you’re playing with fire if you’re stacking these. One study found that nearly half of patients taking blood thinners were also using one or more of these herbs-and most didn’t tell their doctor.

That’s why the Institute for Safe Medication Practices lists Ginkgo as a high-alert herbal product. It’s not because it’s dangerous on its own. It’s because people don’t realize how many other things they’re mixing it with.

Bottom Line

The science is split. Some studies say Ginkgo is fine with blood thinners. Others say it’s a ticking time bomb. The truth? We don’t have perfect data. But we do have real people who bled out after taking both.

If you’re on a blood thinner, the safest choice is to avoid Ginkgo biloba. Not because every study says so-but because the cost of a mistake is too high. A brain bleed doesn’t come with a warning label. And your supplement bottle? It doesn’t know your medical history.

When in doubt, skip it. Talk to your doctor. And if you’re already taking it, don’t ignore it. That bottle on your shelf could be more dangerous than you think.