White willow bark: what it may help and who should never take it
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- Willow bark extract, 15% salicin. Best for: Adults with occasional back pain whose doctor has okayed it. See options on Amazon
- Organic cut white willow bark. Best for: Adults who prefer an herbal tea. See options on Amazon
- White willow bark capsules, plain bark. Best for: Adults comparing single-herb capsules. See options on Amazon
What white willow bark is
Willow is a tree native to Europe, Asia and parts of North America. MSK says its bark has been used for thousands of years in China and Europe for fever and pain. Its main active compound is salicin, and aspirin was developed from salicin.
MSK adds that salicin is not the only active part: catechols and flavonoids in the bark also contribute to its anti-inflammatory effects in lab studies. Supplements are often standardized to salicin; NOW Foods' Willow Bark Extract lists Salix species bark with at least 15% salicin.
What the research shows
| Use | What MSK reports |
|---|---|
| Low back pain | A few trials suggest it may help |
| Osteoarthritis | Mixed results |
| Rheumatoid arthritis | Negative findings |
| Fever | Thought to act like aspirin; no clinical trials |
| Weight loss | No studies |
Back pain. MSK notes clinical trials suggest willow bark extract can help low back pain, including a randomized double-blind study of flare-ups. This is the use with the most support.
Arthritis. Osteoarthritis results are mixed, and studies in rheumatoid arthritis were negative.
Not an aspirin substitute. Aspirin has been studied for heart disease and cancer prevention, but MSK says willow bark should not be used in place of aspirin because its potency varies. A direct comparison between the benefits of aspirin and willow bark cannot be made.
Who should not take willow bark
MSK lists these situations in which you should not take willow bark:
- You take warfarin or other blood thinners, because bleeding risk may rise.
- You take NSAIDs such as ibuprofen or naproxen, because stomach and intestinal damage and bleeding risk may rise.
- You are sensitive or allergic to aspirin or other salicylates.
- You have asthma, breathing problems, or chest or throat tightness.
- You have stomach problems or an ulcer.
- You have a skin rash, hives, or itchy or swollen skin.
MSK also says to stop willow bark before surgery or chemotherapy because of bleeding risk. NOW Foods' label says not for pregnant or nursing women and to consult a physician if you have a bleeding disorder or ulcers or plan surgery.
Never give willow bark to children
MSK warns that children should not be given willow bark because of the potential for Reye syndrome, a serious condition linked to aspirin use in children. MSK also describes a fatal case of liver failure in a 28-month-old boy treated for a respiratory infection with acetaminophen and a tea containing willow bark.
Side effects and case reports
- Common. Stomach or intestinal discomfort, allergic reactions, redness and itching.
- Blood clotting. Salicin affects platelets, though less than aspirin; how much this matters is not known.
- Severe allergy. A 25-year-old woman with aspirin allergy had a serious allergic reaction to a weight-loss supplement containing willow bark.
- Breathing. A 61-year-old woman developed sudden shortness of breath and coughing after taking a willow bark supplement.
Reading a willow bark label
- Salicin percentage. NOW Foods gives 800 mg of willow bark extract with at least 15% salicin per 2 capsules.
- Directions. NOW Foods directs 2 capsules 1 to 2 times daily as needed, with food.
- Ratio extracts and high doses. MSK notes willow bark potency varies, so compare salicin content and follow the label.
- Bark for tea. Cut bark is sold for tea, but strength is hard to know.
- Blends. Joint formulas may combine willow bark with other ingredients; check for anything else that affects bleeding.
What to look for when you buy
Willow bark extract, 15% salicin
Best for: Adults with occasional back pain whose doctor has okayed it
NOW Foods lists 800 mg of extract with at least 15% salicin per 2 capsules, taken with food as needed.
Watch out: Not with aspirin allergy, blood thinners, NSAIDs, ulcers, asthma, pregnancy or before surgery. Never for children.
See options on AmazonOrganic cut white willow bark
Best for: Adults who prefer an herbal tea
Cut and sifted bark is sold for making tea.
Watch out: Salicin content varies. Same cautions as capsules, and never give it to children.
See options on AmazonWhite willow bark capsules, plain bark
Best for: Adults comparing single-herb capsules
Single-herb capsules avoid blends that add other bleeding-related ingredients.
Watch out: Check whether salicin is stated. Follow the label and stop before surgery.
See options on AmazonQuestions people ask
- Is white willow bark the same as aspirin?
- No. Aspirin was developed from salicin in willow bark, but potency varies, and MSK says willow bark should not replace aspirin.
- What is white willow bark good for?
- A few trials suggest it may help low back pain. Results are mixed for osteoarthritis and negative for rheumatoid arthritis.
- Can I take willow bark with ibuprofen?
- MSK says not to. Taking it with NSAIDs may raise the risk of stomach and intestinal damage and bleeding.
- Can children take white willow bark?
- No. Children should not be given willow bark because of the risk of Reye syndrome.
- How much white willow bark should I take?
- Follow the label. NOW Foods directs 2 capsules 1 to 2 times daily as needed with food.
Sources
- Willow Bark: About Herbs (mskcc.org), Memorial Sloan Kettering Cancer Center
- Willow Bark Extract 400 mg Veg Capsules (www.nowfoods.com/products/supplements/willow-bark-extract-400-mg-veg-capsules), NOW Foods