Dong Quai and Warfarin: What You Need to Know About the Bleeding Risk
Dec, 26 2025
When you're on warfarin, even small changes in your diet or supplements can throw your blood clotting off balance. One of the most dangerous but often overlooked combinations is Dong Quai and warfarin. This herbal remedy, used for centuries in Chinese medicine to ease menstrual pain and menopause symptoms, can dramatically increase your risk of serious bleeding when taken with warfarin. It’s not a rumor. It’s not speculation. It’s documented in medical guidelines, case reports, and hospital protocols.
What Is Dong Quai, Really?
Dong Quai, also known as Angelica sinensis, isn’t just another herbal tea. It’s a root used in Traditional Chinese Medicine for over 2,000 years. Women in China have used it for generations to manage periods, hot flashes, and hormonal shifts. Today, it’s sold in health food stores across the U.S. as capsules, teas, and tinctures. Many assume it’s safe because it’s "natural." But "natural" doesn’t mean harmless-especially when you’re on a blood thinner.
Dong Quai contains compounds like ferulic acid and osthole, which interfere with platelet function. In simple terms, they make your blood less likely to clot. That sounds helpful if you’re prone to clots-but when you’re already taking warfarin, it’s like stepping on the gas pedal while your brakes are already pressed.
How Warfarin Works-and Why It’s So Sensitive
Warfarin is one of the most prescribed anticoagulants in the world. Over 30 million prescriptions are filled in the U.S. every year. It works by blocking vitamin K, which your liver needs to make clotting factors. Too little, and you bleed. Too much, and you clot. The goal is to keep your INR (International Normalized Ratio) between 2 and 3 for most conditions. That’s a narrow window. A single point above 4 can mean internal bleeding. A point below 2 means your clot risk goes up.
Unlike newer blood thinners like apixaban or rivaroxaban, warfarin’s effects are highly sensitive to what you eat, drink, and take as supplements. Even small changes in your routine can cause your INR to swing. And Dong Quai is one of the top herbal offenders.
The Science Behind the Interaction
The interaction isn’t just theoretical. Multiple studies show Dong Quai doesn’t just add to warfarin’s effect-it multiplies it. A 2015 review in the British Journal of Clinical Pharmacology found Dong Quai inhibits platelet aggregation, meaning it stops blood cells from sticking together. That’s the same mechanism warfarin uses, just through a different pathway. Together, they create a double hit.
Some research suggests Dong Quai may also slow down how quickly your body breaks down warfarin. It appears to inhibit liver enzymes (CYP2C9 and CYP3A4) that metabolize the drug. If your body can’t clear warfarin fast enough, levels build up. Your INR climbs. And you’re at risk.
A 2014 study published in PMC showed that in animal models, Dong Quai significantly increased prothrombin time-meaning it took longer for blood to clot-without changing warfarin blood levels. That’s a clear sign of a pharmacodynamic interaction: the two drugs work together to amplify the effect, even if one isn’t increasing the other’s concentration.
Real Cases, Real Risks
There aren’t dozens of case reports, but the ones that exist are alarming. One 72-year-old woman in Malaysia went to the ER after her INR jumped from 2.8 to 5.1 after starting Dong Quai for menopausal symptoms. She had no history of bleeding, no other changes in meds or diet. Just Dong Quai. She was hospitalized for observation and required a dose reduction of warfarin.
Online forums like Reddit’s r/anticoagulants have over 17 user reports since 2023 of unexplained INR spikes tied to Dong Quai use. HealthUnlocked forums recorded 23 cases between 2020 and 2023 where patients saw an average INR increase of 1.7 points after starting the herb. That’s enough to push someone from a safe range into the danger zone.
And here’s the scary part: 68% of warfarin users don’t even know herbal supplements can interfere with their medication, according to a 2022 survey by the National Center for Complementary and Integrative Health.
What the Experts Say
Major medical institutions don’t mince words:
- The Cleveland Clinic says: "Avoid Dong Quai in warfarin-treated patients due to lack of data."
- The University of California San Diego lists Dong Quai under "Increased Risk of Bleeding," alongside ginkgo, garlic, and fish oil.
- The Memorial Sloan Kettering Cancer Center warns patients to "consult with their physicians before using this herb," especially if they have hormone-sensitive cancers, because Dong Quai also has estrogen-like effects.
- The American Heart Association classifies Dong Quai as a "high-risk herb" for anticoagulant users.
Dr. Catherine Ulbricht, a leading pharmacist at Massachusetts General Hospital, put it bluntly: "The additive antiplatelet effects of Dong Quai could push a patient’s INR from a therapeutic range of 2.5 to potentially dangerous levels above 4.0."
And she’s right. The annual risk of major bleeding for someone on warfarin is already 1.5-2.5%. Add Dong Quai, and that risk doesn’t just go up-it could double.
Why You Can’t Trust the Label
Here’s another hidden danger: Dong Quai supplements aren’t regulated like drugs. The FDA doesn’t test them for purity, potency, or consistency. A 2020 study by the United States Pharmacopeia found that Dong Quai products varied by up to 8-fold in their active ingredient content. One bottle might have enough ferulic acid to affect your INR. The next bottle from the same brand might have almost none.
That’s why you can’t say, "I took it last week and nothing happened, so it’s fine." Each batch is different. Each person reacts differently. There’s no safe dose you can reliably predict.
What Should You Do?
If you’re on warfarin:
- Stop taking Dong Quai. Even if you feel fine. Even if your doctor didn’t mention it.
- Tell your doctor. Don’t assume they know you’re taking it. Many patients don’t volunteer supplement use because they think it’s "not medicine."
- Get your INR checked. If you’ve taken Dong Quai in the last 2 weeks, ask for a test. It takes 3-5 days for the herb’s effects to show in your blood.
- Ask about alternatives. If you’re using Dong Quai for hot flashes or cramps, ask your doctor about FDA-approved options like low-dose SSRIs, gabapentin, or non-herbal hormonal therapies.
If you’re not on warfarin but considering Dong Quai:
- Ask your doctor if you’re taking any other blood thinners, aspirin, NSAIDs, or supplements like fish oil or garlic.
- Don’t assume "natural" means safe. Many herbs are more potent than people realize.
What About Other Herbs?
Dong Quai isn’t alone. At least 90 Chinese herbal medicines have documented interactions with anticoagulants. Ginkgo, garlic, ginger, turmeric, and ginseng all carry similar risks. In fact, warfarin has more documented herb interactions than any other blood thinner.
And it’s not just Chinese herbs. Even common ones like St. John’s wort can interfere with warfarin metabolism. The bottom line? If you’re on warfarin, assume every supplement is a potential risk until proven otherwise.
What’s Changing?
Regulators are catching up. The European Medicines Agency now requires Dong Quai product labels in EU countries to include a warning about warfarin interactions, effective January 2025. The NIH is funding a major clinical trial at the University of Illinois to study this interaction in humans-results are expected in late 2024.
But until then, the advice remains simple: don’t take Dong Quai if you’re on warfarin. There’s no benefit worth the risk.
Final Thought: Natural Doesn’t Mean Safe
It’s easy to believe that if something’s been used for centuries, it must be harmless. But medicine has evolved. We now know how drugs work at the molecular level. We know how herbs interact with them. And we know that when you mix Dong Quai and warfarin, you’re playing with fire.
Your health isn’t a gamble. Don’t risk bleeding, hospitalization, or worse because you didn’t ask the right question. Talk to your doctor. Get your INR checked. And if you’re taking Dong Quai-stop. Your blood will thank you.
dean du plessis
December 28, 2025 AT 02:46Interesting post. I’ve been on warfarin for atrial fibrillation for 8 years and never heard about Dong Quai. I take turmeric and fish oil regularly-guess I should check with my pharmacist. Thanks for the clarity.
Liz Tanner
December 29, 2025 AT 18:02This is exactly why we need better patient education. So many people think ‘natural’ = ‘safe’ and don’t tell their doctors about supplements. I work in primary care and see this all the time. A simple conversation could prevent a hospital visit.
Alex Lopez
December 30, 2025 AT 08:31Let me just say… if you’re taking Dong Quai on warfarin and you’re still alive, congrats. You’ve won the genetic lottery. Or maybe you just haven’t bled internally yet. Either way, the fact that this isn’t a black-and-white warning on every supplement bottle is a crime. The FDA should be embarrassed.
Caitlin Foster
December 31, 2025 AT 02:41STOP. THE. HERBS. NOW. Seriously. I had a friend who took Dong Quai ‘for balance’ and ended up in the ER with a subdural hematoma. She didn’t even realize it was the herb! It’s not ‘alternative medicine’-it’s ‘alternative risk’!!!
Kylie Robson
January 1, 2026 AT 18:53Actually, the interaction is pharmacokinetic AND pharmacodynamic. The CYP2C9 inhibition increases warfarin plasma concentration, while the antiplatelet effects via osthole and ferulic acid amplify bleeding risk independently. The 2014 animal study you cited didn’t measure plasma levels, so it’s misleading to say warfarin levels didn’t change-those assays aren’t sensitive enough to detect minor shifts in protein binding.
Anna Weitz
January 2, 2026 AT 20:10People don’t realize how much the pharmaceutical industry hates herbs because they can’t patent them. Dong Quai’s been used for millennia. Now you’re telling me it’s dangerous because some lab rats had a longer PT? I’ve been taking it for years. My INR is fine. Who are you to say what’s safe for my body?
Elizabeth Alvarez
January 4, 2026 AT 08:06Did you know that Dong Quai is actually a government experiment to make people bleed so they’ll go to the hospital and get implanted with microchips? The FDA and Big Pharma are in cahoots with the Chinese herbal industry to create dependency. They don’t want you to know that vitamin K2 can reverse everything. The real danger isn’t Dong Quai-it’s the system that hides the truth. Look at the timeline: 2014 study, 2020 FDA non-regulation, 2025 EU warning… it’s all coordinated. They want you scared, dependent, and paying for blood tests every week.
Gerald Tardif
January 6, 2026 AT 06:58Hey, I get it-you’re trying to help. But for people who’ve used Dong Quai for menopause relief for decades, this feels like a betrayal. Maybe instead of just saying ‘stop,’ we could offer safer alternatives? Like black cohosh or lifestyle tweaks? Compassion matters too.
Todd Scott
January 7, 2026 AT 13:33As someone raised in a family that used Dong Quai for menstrual cramps in rural Guangdong, I can tell you-it’s not magic. It’s a mild vasodilator with anti-inflammatory properties. But I also know that in the U.S., people treat it like a wonder drug. The real issue is cultural translation: what’s a gentle tonic in one context becomes a dangerous supplement in another. We need better cross-cultural medical communication, not just warnings.
Babe Addict
January 8, 2026 AT 08:16Bro. You’re acting like Dong Quai is the new heroin. I’ve taken it with warfarin for 3 years. My INR? 2.4. Stable. Your ‘science’ is based on case reports. Correlation ≠ causation. Where’s the RCT? Where’s the p-value? Also, garlic is 10x worse. Why aren’t you banning that? Hypocrite.
Monika Naumann
January 10, 2026 AT 01:42It’s not about natural or synthetic. It’s about discipline. If you can’t follow basic medical advice, then why are you even on warfarin? This isn’t a debate-it’s a failure of personal responsibility. In my country, we don’t mix traditional remedies with modern drugs. We respect boundaries. You should too.