Ginkgo Biloba and Blood Thinners: What You Need to Know About Bleeding Risk

If you’re taking a blood thinner like warfarin, aspirin, or clopidogrel, and you’re also using Ginkgo biloba for memory or circulation, you might be putting yourself at risk-without even knowing it. This isn’t theoretical. People have bled internally after combining the two. One man in his 60s developed spontaneous bleeding in his eye after just one week of taking Ginkgo biloba with low-dose aspirin. Another woman suffered a brain hemorrhage after years of daily Ginkgo use, with no other blood-thinning meds involved. These aren’t rare outliers. They’re documented cases.

What Ginkgo Biloba Actually Does to Your Blood

Ginkgo biloba comes from the leaves of an ancient tree native to China. It’s been sold for decades as a brain booster, but the science behind memory improvement is weak. What’s not weak is its effect on blood clotting. The active compounds in Ginkgo-flavonoid glycosides and terpene lactones-interfere with platelet aggregation. That means your blood cells have a harder time sticking together to form clots. This is exactly what blood thinners are designed to do. When you stack them together, you’re doubling down on the same mechanism.

Standard Ginkgo supplements contain 24% flavonoids and 6% terpenes, with typical doses between 120 and 240 mg per day. That’s the range used in most clinical studies. But here’s the catch: even at these "safe" doses, Ginkgo can push your body past its clotting limit when mixed with other meds.

Which Blood Thinners Are Most Dangerous to Mix With Ginkgo?

Not all blood thinners are created equal, and neither are their interactions with Ginkgo. Some combinations are far riskier than others.

• Warfarin (Coumadin, Jantoven): This is the most documented danger. Multiple case reports show Ginkgo causing spikes in INR levels-sometimes into dangerous territory above 6.0. Normal is 2.0 to 3.0 for most patients. An INR above 4.0 means your blood takes much longer to clot. At 6.0, even a minor bump can cause internal bleeding.
• Clopidogrel (Plavix): This antiplatelet drug is often prescribed after stents or heart attacks. Studies show Ginkgo significantly increases bleeding risk when taken with clopidogrel. One 2007 study in the British Journal of Clinical Pharmacology confirmed this interaction in healthy volunteers.
• Aspirin (80-325 mg): Even low-dose aspirin, taken daily for heart protection, becomes riskier with Ginkgo. The PLOS ONE 2023 study found a clear link between this combo and abnormal bleeding.
• NSAIDs like ibuprofen, naproxen, and celecoxib: These are common painkillers, but they also thin blood. Mixing them with Ginkgo is like pouring gasoline on a small fire.
• Ticagrelor and other newer antiplatelets: These are less studied, but case reports suggest caution is warranted.

Even medications you wouldn’t think are blood thinners can be risky. Omeprazole (Prilosec), used for acid reflux, and nifedipine (Procardia), for high blood pressure, have both been tied to abnormal coagulation tests when combined with Ginkgo. The NIH says this doesn’t always lead to bleeding-but it does mean your body’s clotting system is under strain.

The Contradictory Science: Why Experts Can’t Agree

You might have heard that Ginkgo doesn’t actually increase bleeding risk. That’s because some studies say it doesn’t. A 2023 trial tested EGb 761, a standardized Ginkgo extract, on 29 different blood clotting markers-and found no significant effect. So why do so many people bleed?

The answer lies in the difference between lab tests and real life. Lab studies look at controlled conditions. Real people take multiple drugs, have other health issues, and vary in metabolism. The PLOS ONE study found that while Ginkgo alone didn’t show strong effects in controlled settings, its interaction with other medications created a measurable spike in bleeding risk (OR: 1.08) and abnormal coagulation (OR: 1.49). The problem isn’t Ginkgo alone. It’s Ginkgo + other meds.

Also, not all supplements are equal. The FDA doesn’t regulate herbal products like prescription drugs. One bottle of Ginkgo might have 120 mg of active ingredients. Another might have 50 mg-or even contaminants. That inconsistency makes predicting interactions nearly impossible.

Who Should Never Take Ginkgo Biloba?

If you’re on any blood thinner, stop. That’s the safest rule. But even if you’re not, some people should avoid Ginkgo altogether.

• People with bleeding disorders-like hemophilia or von Willebrand disease.
• Older adults-their livers process drugs slower, so effects last longer.
• Pregnant women-Ginkgo may affect placental blood flow.
• People scheduled for surgery-even minor procedures like dental work or colonoscopies can become dangerous.

The American Society of Anesthesiologists says stop Ginkgo 2 to 3 weeks before surgery. That’s the gold standard. Some researchers argue 36 hours is enough based on how fast it clears the body. But why gamble? A single drop of internal bleeding during surgery can be fatal.

What About Other Supplements and Herbs?

Ginkgo isn’t the only herbal supplement that thins blood. Garlic, ginger, ginseng, and fish oil all have similar effects. If you’re taking one, you might be tempted to add another for "extra benefits." Don’t. The cumulative effect is unpredictable.

And it’s not just blood thinners. Ginkgo can interfere with antidepressants like fluoxetine (Prozac), diabetes meds like metformin, and even seizure drugs like phenytoin. It may reduce their effectiveness. It can also raise blood pressure if taken with decongestants like phenylephrine.

And don’t touch Ginkgo seeds. They’re toxic. Eating them-even roasted-can cause seizures, vomiting, and loss of consciousness. Stick to leaf extracts, and even then, proceed with caution.

What Should You Do If You’re Already Taking Both?

If you’re on a blood thinner and already taking Ginkgo biloba, don’t panic. But don’t ignore it either.

1. Talk to your doctor or pharmacist. Bring your full list of supplements and meds. Many people forget to mention herbal products. They think it’s "natural," so it’s safe. It’s not.
2. Get a blood test. If you’re on warfarin, ask for an INR check. If it’s higher than normal, Ginkgo could be the cause.
3. Stop Ginkgo. If you’re planning surgery, stop it now. If you’re not, consider stopping anyway. The benefits for memory are unproven. The risks are real.
4. Use a medication tracker. Apps or paper lists help you and your doctor see what you’re really taking. Don’t rely on memory.

Pharmacists are your best ally here. They see hundreds of drug interactions every week. They know which ones are dangerous and which ones are myths. Ask them. Don’t wait for your doctor to bring it up.

Bottom Line: Natural Doesn’t Mean Safe

Ginkgo biloba is marketed as a "natural" way to improve brain function. But "natural" doesn’t mean harmless. It’s a powerful plant extract with real, measurable effects on your blood. When mixed with prescription blood thinners, it can turn a routine day into a medical emergency.

The data isn’t perfect. Some studies say no risk. Others say yes. But the case reports are consistent. People bleed. Sometimes they die. And it’s preventable.

If you’re taking any anticoagulant or antiplatelet drug-whether it’s a prescription or over-the-counter like aspirin-avoid Ginkgo biloba. Period. There’s no safe dose when you’re already thinning your blood. The potential benefit? Unclear. The risk? Real. And it’s not worth it.