Feverfew-Anticoagulant Risk Calculator
This tool estimates your bleeding risk when taking feverfew with blood thinners based on current medical knowledge.
Note: This is a general assessment, not a medical diagnosis. Always consult your healthcare provider before changing your medications.
Your Risk Assessment
You are not currently taking feverfew with anticoagulants. There is minimal bleeding risk.
Feverfew is generally safe when not combined with blood thinners. However, the article notes that feverfew can cause bleeding risk when taken with anticoagulants. It may also cause withdrawal symptoms if stopped abruptly after long-term use.
When you’re taking blood thinners like warfarin, apixaban, or rivaroxaban, even small changes in your routine can affect how well they work. That includes something as simple as popping a feverfew capsule for migraines. Feverfew isn’t just another herbal remedy-it’s a plant with real, measurable effects on your blood’s ability to clot. And when it’s mixed with anticoagulants, the risk isn’t theoretical. It’s documented. One case from 2021 showed a 36-year-old woman with a prothrombin time (PT) of 27.3 seconds-more than double the normal range-after taking feverfew daily for months. Her numbers only returned to normal after she stopped it for four months.
What Is Feverfew, Really?
Feverfew (Tanacetum parthenium) is a daisy-like herb that’s been used for over 2,000 years. Ancient Greeks chewed its leaves to reduce fever, hence the name. Today, people take it mostly to prevent migraines. The active ingredient, parthenolide, works by blocking serotonin from triggering platelet clumping-a key step in blood clotting. That’s why it helps with headaches: it reduces inflammation and stops blood vessels from constricting too hard.
But here’s the catch: if your blood can’t clot properly because of a prescription anticoagulant, and feverfew also slows clotting, you’re stacking two effects on top of each other. The result? Longer bleeding times, more bruising, nosebleeds that won’t stop, or worse-internal bleeding after a fall or surgery.
The Bleeding Risk Isn’t Just a Theory
There’s only one published case of feverfew causing serious coagulopathy in a person on anticoagulants. But that’s not the whole story. In a 2020 survey of 300 feverfew users, 11.3% got mouth sores from chewing fresh leaves. That’s a clue: if the plant irritates your mouth lining, it’s active in your body. And in online forums like Reddit’s r/herbalremedies, 27 users reported easy bruising or nosebleeds lasting 15-45 minutes after combining feverfew with low-dose aspirin. That’s not coincidence. That’s a pattern.
What makes feverfew different from other herbs is its mechanism. Unlike garlic or ginger, which affect multiple clotting pathways, feverfew mostly targets serotonin-induced platelet aggregation. That sounds specific, but in people on anticoagulants, even one pathway being blocked can tip the balance. The NIH case report showed PT and PTT levels stayed abnormal for months after stopping feverfew. That’s not something you want to gamble with.
How Feverfew Interacts With Common Blood Thinners
Feverfew doesn’t just affect platelets. It also interferes with liver enzymes-specifically CYP2C9 and CYP3A4-that break down warfarin and other anticoagulants. In lab studies, feverfew can raise warfarin levels in the blood by 18-22%. That means even if you’re taking the same dose, your body might be getting more of the drug than you think. That’s dangerous.
For warfarin users, this is especially risky because the drug has a narrow safety window. Too little, and you’re at risk for clots. Too much, and you bleed. INR levels need to stay between 2 and 3. A feverfew capsule could push you over that line without warning.
For newer anticoagulants like apixaban or rivaroxaban, the data is thinner-but not zero. A 2023 clinical trial (NCT05567891) is currently studying how feverfew affects apixaban in 120 healthy volunteers. Preliminary results are due in mid-2024. Until then, assume the same risk applies. No evidence of harm isn’t the same as proof of safety.
What the Experts Say
Dr. Donald Abrams from Zuckerberg San Francisco General Hospital says: “Feverfew may increase bleeding risk when combined with anticoagulants, though clinical relevance is not definitively established.” That’s cautious language, but it’s not a green light. Dr. Jun Mao at Memorial Sloan Kettering adds: “The active constituent inhibits platelet activity and may have additive effects.” He doesn’t say it’s common. He says it can happen.
The American College of Chest Physicians and the American Society of Anesthesiologists both recommend stopping feverfew at least 14 days before surgery. For high-risk procedures-like spinal taps or heart surgery-they suggest 21 days. Why so long? Because feverfew doesn’t just leave your system quickly. It lingers in your platelets. And if you’re about to go under the knife, you don’t want your blood to behave unpredictably.
The Withdrawal Problem Nobody Talks About
Here’s a twist: stopping feverfew suddenly can cause its own problems. About 41% of people who’ve taken it daily for months report severe headaches after quitting. Others get insomnia, joint pain, or nervousness. This is called “post-feverfew syndrome.” In one study, 32% had trouble sleeping, 27% had muscle stiffness, and 24% felt anxious-all within days of quitting.
That’s why experts recommend tapering off, not stopping cold turkey. If you’ve been taking feverfew for over a year, cut your dose by 25% every 3-5 days. Give your body time to adjust. This isn’t just about avoiding headaches. It’s about making sure your blood clotting system doesn’t go into shock when the herb leaves your system.
Who Should Avoid Feverfew Altogether?
If you’re on any anticoagulant-warfarin, Xarelto, Eliquis, Pradaxa, or even low-dose aspirin-feverfew is not worth the risk. The data is limited, but the consequences aren’t. One case of abnormal bleeding can turn into a hospital stay, a blood transfusion, or worse.
Other groups should also steer clear:
- Pregnant or breastfeeding women-no safety data exists
- People with liver or kidney disease-feverfew is processed through both organs
- Anyone scheduled for surgery-14 to 21 days before is the safe window
- Those with allergies to ragweed, daisies, or chrysanthemums-feverfew is in the same plant family
Even if you’ve taken it for years without issues, that doesn’t mean it’s safe. Your body changes. Your medications change. Your liver enzymes change. What worked last year might not work this year.
What About Other Herbs Like Ginger or Ginkgo?
Feverfew is part of a group called the “Few Gs”: feverfew, ginger, ginkgo, garlic, and ginseng. These are the top five herbal supplements linked to bleeding risk. But they’re not equal.
Ginkgo has more documented cases of interaction with warfarin-12 in the FDA database alone. Garlic and ginger clear from your system in about 72 hours. Feverfew? It sticks around. And unlike ginseng, which mainly affects platelet function, feverfew also messes with liver enzymes that metabolize your blood thinners. That’s a double hit.
Dong quai is even riskier-it contains natural coumarin, which acts like warfarin. But feverfew doesn’t need to contain coumarin to cause problems. Its effect is indirect, which makes it harder to predict.
What Should You Do?
If you’re taking anticoagulants and using feverfew:
- Stop immediately. Don’t wait for symptoms.
- Tell your doctor. Bring the bottle. Say exactly what you’re taking and how much.
- Get a PT/INR and PTT test. Baseline numbers matter.
- If you’re scheduled for surgery, stop at least 14 days ahead. For major procedures, aim for 21 days.
- If you’ve been taking it long-term, taper off slowly: reduce by 25% every few days.
If you’re not on anticoagulants but want to try feverfew for migraines:
- Use encapsulated forms. Chewing fresh leaves causes mouth sores in 1 in 9 people.
- Look for products standardized to 0.2-0.7% parthenolide.
- Start low-50mg daily-and monitor for bruising or bleeding.
- Don’t combine it with other herbs that thin blood, like turmeric or omega-3s.
The Bottom Line
Feverfew isn’t dangerous on its own. But when you’re on blood thinners, it becomes a hidden variable. You can’t see it. You can’t measure it. And by the time you notice symptoms-bruising, nosebleeds, heavy periods-it might already be too late.
The FDA hasn’t issued a warning about feverfew yet. But they’ve warned about ginkgo 11 times. That doesn’t mean feverfew is safe. It just means fewer people have reported problems. That could change tomorrow.
For now, the safest choice is simple: if you’re on anticoagulants, skip feverfew. There are other migraine preventatives-magnesium, riboflavin, coenzyme Q10-that don’t interfere with your blood thinners. Why risk it?
Herbs aren’t harmless. They’re powerful. And when they mix with prescription drugs, the consequences aren’t always obvious until it’s too late.
Deborah Jacobs
December 5, 2025 AT 15:54I’ve been taking feverfew for migraines for 5 years-no issues. But reading this made me pause. I never thought about how it might be quietly messing with my blood. I’m gonna call my doctor tomorrow and get my INR checked. Better safe than sorry.
Also, thanks for mentioning the tapering thing. I had no idea quitting cold turkey could cause headaches worse than the migraines themselves. Mind blown.
James Moore
December 6, 2025 AT 22:21Let me get this straight-you’re telling me that a plant that’s been used since ancient Greece, chewed by Hippocrates himself, is suddenly dangerous because some lab rats in a 2021 case study had a PT of 27.3? That’s not science-that’s fearmongering dressed up as medicine!
Meanwhile, Big Pharma is selling you $1,000-a-month pills that turn your liver into a pile of ash and your gut into a warzone, but you’re terrified of a daisy? The real danger isn’t feverfew-it’s the pharmaceutical cartel that needs you dependent on their synthetic crap. Wake up, people!
And don’t even get me started on ‘standardized parthenolide’-that’s just corporate greed repackaging nature into a patentable pill. Nature doesn’t come in capsules. It comes in leaves. Chew the damn thing. Build resilience. Stop being a lab rat for Big Med.
Chris Brown
December 7, 2025 AT 10:07It is, in fact, irresponsible to suggest that herbal remedies are benign simply because they are ‘natural.’ The notion that ‘natural equals safe’ is a dangerous fallacy, one that has led to countless hospitalizations. The fact that feverfew affects platelet aggregation is not speculative-it is biochemically demonstrable. To ignore this is to ignore the very foundation of pharmacology.
Moreover, the claim that ‘few cases have been reported’ is statistically meaningless. A single case of catastrophic bleeding is one case too many. The absence of evidence is not evidence of absence. And yet, people continue to treat medicine like a buffet-take what sounds nice, ignore the fine print, and hope for the best.
This is not a debate. It is a public health imperative.
Mark Curry
December 8, 2025 AT 21:03Good post. I’ve been on Xarelto for AFib and was taking ginger tea every day. Didn’t realize how many herbs can do this. I stopped the ginger after reading this. No more risky combos for me.
Also, the tapering tip was super helpful. I’ve been trying feverfew for months and didn’t know quitting could mess with my sleep. Going to cut back slowly now. Thanks for the clarity 😊
Manish Shankar
December 10, 2025 AT 15:36Thank you for this meticulously researched and clinically grounded exposition. In the Indian context, where traditional herbal remedies are often conflated with pharmaceutical-grade safety, such warnings are not merely prudent-they are essential.
Many patients self-administer feverfew under the assumption that ‘Ayurveda is gentle,’ unaware that the pharmacokinetic interactions are no less potent than synthetic agents. The case of prolonged coagulopathy after discontinuation underscores the need for formal integration of herbal pharmacology into clinical training. I shall share this with my colleagues at AIIMS.
With profound respect for your diligence.
Rupa DasGupta
December 12, 2025 AT 13:19OMG I’ve been taking feverfew with Eliquis for 3 years 😱
I thought it was ‘natural’ so it was fine. I’ve had nosebleeds since last winter but I just blamed the dry air. What if I bleed out in my sleep?!
Also-why isn’t the FDA warning about this?! This is a cover-up. They don’t want you to know herbs are safer than pills. I’m posting this everywhere. #FeverfewCoverUp #BigPharmaLies 💔
Marvin Gordon
December 13, 2025 AT 18:02Man, this is the kind of post that saves lives. No fluff. Just facts. I’ve got a buddy on warfarin who swears by feverfew for his migraines. I’m sending him this right now.
Also, the tapering advice? Gold. People think quitting anything cold turkey is ‘strong,’ but your body doesn’t work like a light switch. Respect the process.
Thanks for doing the work so we don’t have to.
ashlie perry
December 14, 2025 AT 10:21They’re lying. Feverfew is fine. The whole ‘bleeding risk’ thing is a distraction. The real danger is the chemicals in your blood thinner. That’s what’s killing people. Feverfew is being framed as the villain so they can sell you more expensive pills. You think they want you to heal? They want you addicted.
And why is the NIH studying it? Because they’re trying to patent the active ingredient. They don’t want you using the plant. They want you buying the pill.
Stop trusting the system. Trust your body. 🤫
Michael Dioso
December 16, 2025 AT 10:03Wow. Someone actually wrote a coherent, evidence-based piece about herbal interactions. Imagine that. Not a single mention of ‘detox’ or ‘energy flow.’ Shocking.
Also, the fact that they cited a clinical trial number? NCT05567891? That’s not Reddit. That’s a medical journal. I’m almost impressed.
Still, the real problem isn’t feverfew-it’s that people think they can self-diagnose migraines and treat them with plants instead of seeing a neurologist. But hey, at least this post didn’t say ‘just meditate’ or ‘you’re stressed.’ Progress.
sean whitfield
December 16, 2025 AT 16:01So let me get this straight. A plant that’s been around since the Greeks is now ‘dangerous’ because a 36-year-old woman took it for months and got a weird blood test? And now we’re supposed to panic?
Meanwhile, every single pharmaceutical drug has killed more people than all herbal supplements combined. But we’re gonna ban a daisy because someone’s PT was high? That’s not science. That’s fear.
Also, why does everyone assume the ‘experts’ know better? They got paid to say that. I’ll chew my feverfew leaves and die on my own terms thanks.
PS: The ‘tapering’ advice? That’s just Big Med trying to make you dependent on their withdrawal protocols. Just quit. Be strong.
Stephanie Bodde
December 17, 2025 AT 11:36Thank you for this. I’ve been on warfarin for 7 years and started feverfew last year because my migraines got worse. I had no idea. I’m stopping today. And I’m going to taper slowly like you said. You saved me from a disaster 💕
Also-please write more posts like this. We need more people who care enough to explain the science without the fear.
Philip Kristy Wijaya
December 17, 2025 AT 16:15It is not merely a matter of pharmacological interaction-it is a moral imperative. To knowingly consume a botanical agent with documented anticoagulant properties while under prescription therapy constitutes a dereliction of personal responsibility. One does not casually engage with substances that alter hemostatic function without informed consent.
Furthermore, the casual dismissal of clinical evidence in favor of anecdotal experience is not merely unscientific-it is ethically indefensible. The individual who suffers hemorrhagic complications does not do so in isolation. Their family, their caregivers, their emergency responders-all bear the burden of that negligence.
Let this serve as a clarion call: knowledge is not optional. Ignorance is a choice-and it is lethal.
William Chin
December 18, 2025 AT 12:08As a pharmacist with 22 years in clinical practice, I’ve seen three patients with major bleeding events tied to feverfew + anticoagulants. Two needed transfusions. One died. The third was a 78-year-old woman who said, ‘It’s just a herb.’
It’s not just ‘theoretical.’ It’s in the charts. I’ve documented it. I’ve reported it. And I’ve watched families cry in the ICU because someone thought ‘natural’ meant ‘safe.’
If you’re on blood thinners and taking feverfew-you’re playing Russian roulette with your own organs. Stop. Now.
Ada Maklagina
December 20, 2025 AT 09:47Been on rivaroxaban for 4 years. Took feverfew for 6 months. No bruising. No nosebleeds. No problems.
Maybe it’s not dangerous for everyone? Maybe the risk is overblown?
Just saying. Not everyone’s body reacts the same.
Harry Nguyen
December 20, 2025 AT 16:30Oh great. Another anti-herb propaganda piece from the American medical-industrial complex. We’re supposed to trust the FDA-who approved Vioxx, OxyContin, and now the latest cancer drug that costs $500K a year-but not trust a plant that’s been used for millennia?
And why is this only about feverfew? What about turmeric? Omega-3s? Green tea? All of them affect clotting. But you don’t see headlines screaming about those. Why? Because they can’t patent them.
This isn’t about safety. It’s about control. And you’re falling for it.