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

Every year, over 1.5 million Americans take Ginkgo biloba hoping to boost memory or improve circulation. But if you're on blood thinners-whether it's aspirin, warfarin, or clopidogrel-this popular herb could be quietly putting you at risk for serious bleeding. It’s not a myth. It’s not speculation. It’s documented in hospital records, case studies, and clinical guidelines. And most people have no idea.

How Ginkgo Biloba Affects Your Blood

Ginkgo biloba comes from the leaves of an ancient tree native to China. The extract used in supplements typically contains 24% flavonoid glycosides and 6% terpene lactones. That’s the standard formula you’ll see on bottles labeled as “standardized extract.” Doses usually range from 120 to 240 mg per day. For some, it feels harmless-just another pill in the morning routine.

But here’s what most labels don’t tell you: Ginkgo biloba interferes with platelet aggregation. That means it makes it harder for your blood to clot. It doesn’t thin your blood like warfarin does. Instead, it works on the same pathway as aspirin and clopidogrel. When you combine them, the effect isn’t just added-it’s multiplied.

A 2023 study in PLOS ONE found that people taking Ginkgo biloba along with common blood thinners had a 49% higher chance of abnormal coagulation test results. That’s not a small bump. That’s a red flag on a lab report.

Which Blood Thinners Are Dangerous with Ginkgo?

Not all blood thinners are the same. But when paired with Ginkgo biloba, several carry clear, documented risks:

• Warfarin (Coumadin, Jantoven): Cases show INR levels spiking dangerously high-sometimes above 6.0-within days of starting Ginkgo. An INR over 4.5 means your blood takes over four times longer to clot. That’s a one-way ticket to internal bleeding.
• Clopidogrel (Plavix): A 2007 study in the British Journal of Clinical Pharmacology confirmed that Ginkgo reduces clopidogrel’s effectiveness while still increasing bleeding risk. It’s a double-edged sword.
• Aspirin (80-325 mg): Even low-dose aspirin for heart protection becomes riskier. One man developed spontaneous bleeding in his eye after just one week of taking 80 mg aspirin plus Ginkgo.
• Ticagrelor, Etoricoxib, Nifedipine: These aren’t classic blood thinners, but they interact with Ginkgo in ways that disrupt clotting. Ticagrelor, for example, is used after stents. Mixing it with Ginkgo can lead to uncontrolled bleeding.
• NSAIDs like ibuprofen, celecoxib, loxoprofen: These over-the-counter painkillers already raise bleeding risk. Add Ginkgo, and you’re stacking the deck.

And here’s the kicker: You don’t even need to be on a prescription blood thinner to be at risk. One woman suffered a brain hemorrhage after taking Ginkgo daily for years-no other medications involved. Her body just couldn’t handle the cumulative effect.

The Contradictory Evidence-And Why It Doesn’t Change Anything

You might have heard that some studies say Ginkgo doesn’t affect clotting. That’s true. One trial using the standardized extract EGb 761 tested 29 different coagulation markers and found no significant changes. So why the panic?

Because lab tests don’t always capture real-world outcomes. Clinical trials measure controlled variables. Real people take Ginkgo with other meds, have underlying conditions, or take higher doses. The PLOS ONE study found that while the extract itself didn’t show inhibition in a controlled setting, the combination with other drugs consistently triggered bleeding events.

The NIH study in 2024 confirmed this: Ginkgo didn’t directly cause bleeding in most cases, but it made abnormal coagulation test results more likely-especially when combined with omeprazole, insulin, or domperidone. That’s not a coincidence. That’s a pattern.

Case reports don’t lie. A man on warfarin started Ginkgo. His INR jumped from 2.8 to 7.1 in five days. He needed a transfusion. Another patient had a gastrointestinal bleed after combining Ginkgo with daily aspirin. Both had no history of bleeding before.

Who Should Avoid Ginkgo Biloba Entirely?

If you fall into any of these groups, stop reading and put the bottle down:

• Anyone on anticoagulants or antiplatelet drugs-even low-dose aspirin.
• People over 65: Aging reduces liver and kidney function. Your body clears Ginkgo slower. Risk goes up.
• Those with bleeding disorders: Hemophilia, von Willebrand disease, or even a history of easy bruising.
• Pregnant or breastfeeding women: Ginkgo can cross the placenta. There’s no safe dose established.
• People scheduled for surgery: Even minor procedures like dental work or colonoscopies carry bleeding risk.

The American Society of Anesthesiologists says: Stop Ginkgo 2 to 3 weeks before any planned surgery. That’s not a suggestion. That’s a safety protocol. Some researchers argue 36 hours might be enough based on how quickly the body clears it. But why gamble? A brain bleed doesn’t come with a warning.

What About Over-the-Counter Products?

The FDA doesn’t regulate supplements like it does prescription drugs. That means two bottles of Ginkgo labeled “120 mg” can have wildly different amounts of active ingredients-or even contaminants. One 2023 review found that 37% of Ginkgo supplements on the market didn’t match their label claims.

And here’s something rarely discussed: Ginkgo seeds are poisonous. Roasted or raw, they contain ginkgotoxin, which can cause seizures. Don’t eat them. Don’t even think about it.

Supplements are big business. The U.S. market for Ginkgo biloba brings in about $100 million a year. Companies profit from vague claims like “supports brain health.” But they don’t have to prove safety before selling. That’s the loophole in the Dietary Supplement Health and Education Act of 1994.

What Should You Do?

Here’s your action plan:

1. Check every medication you take. Include OTC painkillers, heart meds, antidepressants, and even cold remedies. Ginkgo interacts with more than 15 common drugs.
2. Talk to your pharmacist. They see drug interactions every day. Bring your bottle or a list. Don’t say “I take a natural supplement.” Say “I take Ginkgo biloba 120 mg daily.” Specificity saves lives.
3. Stop Ginkgo before surgery. Even if your doctor doesn’t ask, tell them. And do it at least two weeks out.
4. Watch for signs of bleeding. Unexplained bruising, nosebleeds that won’t stop, blood in urine or stool, sudden headaches, or vision changes. If you’re on Ginkgo and any of these happen, go to the ER.
5. Don’t assume “natural” means safe. Ginkgo isn’t harmless. It’s a powerful plant compound with documented effects on your blood.

If you’re taking Ginkgo for memory or circulation, know this: There’s no strong evidence it works for either. The NIH says the data is “limited.” If you’re risking a brain bleed for a maybe benefit, it’s not worth it.

Alternatives to Ginkgo Biloba

If you’re using Ginkgo for cognitive support, try proven, safer options:

• Regular aerobic exercise: Walking 30 minutes a day improves blood flow to the brain better than any supplement.
• Mediterranean diet: Rich in omega-3s, antioxidants, and healthy fats-linked to slower cognitive decline.
• Omega-3 supplements (fish oil): Proven to support brain health without bleeding risk when taken at standard doses.
• Vitamin B12 and folate: Deficiencies are common in older adults and directly linked to memory problems. Test your levels.

None of these carry the same bleeding risk. None require you to stop taking them before surgery. And they actually work.

Final Thought

Ginkgo biloba isn’t a villain. But it’s not a harmless herb either. It’s a powerful plant extract with real, measurable effects on your blood. If you’re on any kind of blood thinner-prescription or over-the-counter-you’re playing Russian roulette with your health. The evidence isn’t uncertain. The risk is real. And the consequences? They’re permanent.

Stop taking it. Talk to your doctor. Find safer ways to support your brain and circulation. Your future self will thank you.