What is it?
Willow bark acts a lot like aspirin. It's most commonly used for pain and fever. But there is no good scientific evidence to show that it works as well as aspirin for these conditions.
Coronavirus disease 2019 (COVID-19): Some experts warn that willow bark may interfere with the body's response against COVID-19. There is no strong data to support this warning. But there is also no good data to support using willow bark for COVID-19.
How effective is it?
Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
The effectiveness ratings for WILLOW BARK are as follows:
Possibly effective for...
- Back pain. Willow bark seems to reduce lower back pain. Higher doses seem to be more effective than lower doses. It can take up to a week for significant improvement.
Insufficient evidence to rate effectiveness for...
- Joint pain. Research shows that taking a specific product containing white willow bark extract and other ingredients for 8 weeks reduces joint pain. But taking this product doesn't seem to help joint stiffness or function.
- Obesity. Early research suggests that taking willow bark in combination with ephedra and cola nut might cause slight weight loss in overweight and obese people. But it is not wise to use this combination because of safety concerns about ephedra. Ephedra has been banned in the United States due to severe harmful side effects.
- Osteoarthritis. Research on willow bark extract for osteoarthritis has produced conflicting results. Some research shows it can reduce osteoarthritis pain. In fact, there is some evidence suggesting that willow bark extract works as well as conventional medications for osteoarthritis. But other research shows no benefit.
- Rheumatoid arthritis (RA). Early research suggests that willow bark extract is not effective for RA.
- A type of arthritis that mainly affects the spine (ankylosing spondylitis).
- Common cold.
- Flu (influenza).
- Menstrual cramps (dysmenorrhea).
- Muscle pain.
- Swine flu.
- Other conditions.
How does it work?
Are there safety concerns?
Special precautions & warnings:Pregnancy: There isn't enough reliable information to know if willow bark is safe to use when pregnant. Stay on the safe side and avoid use.
Breast-feeding: Using willow bark while breast-feeding is POSSIBLY UNSAFE. Willow bark contains chemicals that can enter breast milk and have harmful effects on the nursing infant. Don't use it if you are breast-feeding.
Children: Willow bark is POSSIBLY UNSAFE n children when taken by mouth for viral infections such as colds and flu. There is some concern that, like aspirin, it might increase the risk of developing Reye's syndrome. Stay on the safe side and don't use willow bark in children.
Bleeding disorders: Willow bark might increase the risk of bleeding in people with bleeding disorders.
Kidney disease: Willow bark might reduce blood flow through the kidneys. This might lead to kidney failure in some people. If you have kidney disease, don't use willow bark.
Sensitivity to aspirin: People with ASTHMA, STOMACH ULCERS, DIABETES, GOUT, HEMOPHILIA, HYPOPROTHROMBINEMIA, or KIDNEY or LIVER DISEASE might be sensitive to aspirin and also willow bark. Using willow bark might cause serious allergic reactions. Avoid use.
Surgery: Willow bark might slow blood clotting. There is a concern it could cause extra bleeding during and after surgery. Stop using willow bark at least 2 weeks before a scheduled surgery.
Are there interactions with medications?
- Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)
- Willow bark might slow blood clotting. Taking willow bark along with medications that also slow blood clotting might increase the chances of bruising and bleeding.
Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, warfarin (Coumadin), and others.
- Willow bark contains chemicals that might increase the amount of acetazolamide in the blood. Taking willow bark along with acetazolamide might increase the effects and side effects of acetazolamide.
- Willow bark contains chemicals similar to aspirin. Taking willow bark along with aspirin might increase the effects and side effects of aspirin.
- Choline Magnesium Trisalicylate (Trilisate)
- Willow bark contains chemicals that are similar to choline magnesium trisalicylate (Trilisate). Taking willow bark along with choline magnesium trisalicylate (Trilisate) might increase the effects and side effects of choline magnesium trisalicylate (Trilisate).
- Salsalate (Disalcid)
- Salsalate (Disalcid) is a type of medicine called a salicylate. It's similar to aspirin. Willow bark also contains a salicylate similar to aspirin. Taking salsalate (Disalcid) along with willow bark might increase the effects and side effects of salsalate (Disalcid).
Are there interactions with herbs and supplements?
- Herbs and supplements that might slow blood clotting
- Willow bark can slow blood clotting. Using it along with other herbs that can also slow blood clotting might increase the chance of bleeding and bruising in some people. These herbs include clove, danshen, garlic, ginger, ginkgo, ginseng, meadowsweet, red clover, and others.
- Herbs that contain chemicals similar to aspirin (salicylates)
- Willow bark contains a chemical that is similar to an aspirin-like chemical called salicylate. Taking willow bark along with herbs that contain salicylate may increase salicylate effects and adverse effects. Salicylate-containing herbs include aspen bark, black haw, poplar, and meadowsweet.
Are there interactions with foods?
- There are no known interactions with foods.
What dose is used?
- For back pain: Willow bark extract providing 120-240 mg salicin has been used. The higher 240 mg dose might be more effective.
To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.
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