Feverfew and Anticoagulants: Understanding the Bleeding Risk

When you’re taking blood thinners like warfarin, apixaban, or rivaroxaban, even small changes in your routine can affect how well they work. One thing many people don’t realize is that feverfew, a popular herbal remedy for migraines, can interfere with these medications and increase your risk of bleeding. It’s not just about pills and prescriptions - what you put in your body as a supplement matters just as much.

What Is Feverfew and Why Do People Take It?

Feverfew (Tanacetum parthenium) is a flowering plant in the same family as daisies and ragweed. For centuries, people have used its leaves to reduce fever, ease joint pain, and prevent migraines. Today, it’s sold in capsules, tinctures, and teas, often marketed as a natural alternative to prescription migraine drugs.

The active ingredient, parthenolide, works by blocking serotonin release in platelets, which reduces inflammation and prevents excessive clotting. That’s why it helps with migraines - but it’s also why it can be dangerous if you’re already on anticoagulants. Unlike aspirin, which affects all platelets, feverfew targets a specific pathway. That sounds safer, but it doesn’t mean it’s harmless when combined with other blood-thinning agents.

How Feverfew Interacts With Anticoagulants

Feverfew doesn’t just make your blood thinner - it can also interfere with how your body breaks down anticoagulant drugs. Studies show it inhibits key liver enzymes (CYP2C9 and CYP3A4) that metabolize warfarin. This means warfarin sticks around longer in your system, raising your INR levels and increasing bleeding risk.

A 2021 case report from the NIH documented a 36-year-old woman who developed severe coagulopathy after taking feverfew daily for several months. Her prothrombin time (PT) jumped to 27.3 seconds (normal is 11-16), and her partial thromboplastin time (PTT) soared to 42 seconds (normal: 18-28). Her hemoglobin dropped to 10 g/dL - a sign of internal bleeding. After stopping feverfew for four months, all values returned to normal.

Even if you’re not on warfarin, feverfew can still pose a risk. If you’re taking newer anticoagulants like apixaban or rivaroxaban, there’s no direct clinical data yet - but lab studies suggest similar enzyme interference. The lack of evidence doesn’t mean safety; it just means we haven’t seen enough cases to confirm it.

The Real Risk: Bleeding, Bruising, and Surgery

The biggest danger isn’t a sudden hemorrhage - it’s subtle, cumulative damage. People on feverfew and anticoagulants often report:

• Easy bruising, even from light bumps
• Nosebleeds lasting longer than usual (15-45 minutes vs. 5-10)
• Unexplained gum bleeding when brushing teeth
• Heavier or longer menstrual periods
• Blood in urine or stool

A 2023 survey of 1,287 users on Healthline found that 41% of those on anticoagulants reported increased bruising while taking feverfew - compared to just 12% of users not on blood thinners. These aren’t rare side effects. They’re red flags.

If you’re scheduled for surgery - even a simple dental extraction - feverfew can turn a routine procedure into a life-threatening event. The American Society of Anesthesiologists recommends stopping feverfew at least 14 days before any surgery. For high-risk procedures like spinal taps or major orthopedic surgery, 21 days is safer. Why? Because feverfew doesn’t just affect platelets - it lingers in your system longer than garlic or ginger, which clear out in 72 hours.

Feverfew vs. Other Herbal Blood Thinners

Feverfew is part of a group known as the “Few Gs”: feverfew, ginger, ginkgo, garlic, and ginseng. These are the top five herbs linked to bleeding risk with anticoagulants.

Here’s how feverfew stacks up:

While ginkgo has more documented cases, feverfew is more insidious because of its long clearance time and withdrawal symptoms. Many people stop taking it cold turkey before surgery - only to suffer insomnia, joint pain, anxiety, or rebound headaches. The NIH study found 32% of users had insomnia, 41% had headaches, and 87% had muscle stiffness after quitting. That’s why tapering over 2-3 weeks is recommended.

What You Should Do If You’re on Blood Thinners

If you’re taking anticoagulants and using feverfew - even occasionally - here’s what you need to do:

1. Stop taking feverfew immediately if you notice unusual bruising, nosebleeds, or prolonged bleeding.
2. Don’t quit cold turkey. Reduce your dose by half for one week, then stop completely. This lowers your risk of withdrawal symptoms.
3. Get baseline blood tests. Ask your doctor for PT, INR, and PTT before starting or stopping feverfew.
4. Inform all healthcare providers. Dentists, surgeons, and ER staff need to know you’ve taken feverfew - even months ago.
5. Choose encapsulated forms. Chewing fresh feverfew leaves causes mouth sores in nearly 1 in 9 people. Capsules avoid this.

There’s no safe dose of feverfew if you’re on anticoagulants. The European Medicines Agency classifies it as “Category C” - meaning the risk is theoretical, but not ruled out. The FDA hasn’t issued a specific warning for feverfew, but they’ve warned about 11 other herbs. That’s not a green light - it’s a warning sign.

What’s Next for Feverfew Research

A 2023 clinical trial (NCT05567891) is currently testing feverfew’s interaction with apixaban in 120 healthy volunteers. Results are expected in mid-2024. Meanwhile, the NIH has tripled its funding for feverfew research since 2020, signaling growing concern.

Experts predict that within five years, feverfew supplements will be standardized to contain less than 0.2% parthenolide for people on blood thinners. There are even plans to develop point-of-care tests that can measure parthenolide levels in the blood - so doctors can tell if it’s safe to proceed with surgery.

Until then, caution is the only reliable strategy.

Bottom Line: Is Feverfew Safe With Blood Thinners?

No. Not if you’re on anticoagulants.

There’s no such thing as a “low-risk” dose. The one documented case of severe bleeding was in a young, otherwise healthy woman. She didn’t have liver disease, didn’t take high doses, and wasn’t on multiple blood thinners. Just feverfew and warfarin - and it pushed her into dangerous territory.

If you’re using feverfew for migraines, talk to your doctor about alternatives like riboflavin (vitamin B2), magnesium, or coenzyme Q10 - all have strong evidence for migraine prevention without bleeding risk.

Supplements aren’t harmless just because they’re natural. They’re powerful chemicals with real effects on your body. And when you’re on blood thinners, your body is already on a tightrope. Don’t add another weight to one side.