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 this extract 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 this 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 this 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.
More evidence is needed to rate the effectiveness of this extract for these uses.
Side Effects Of Willow Bark
When taken by mouth: Willow bark is POSSIBLY SAFE for most adults when taken for up to 12 weeks. It may cause headaches, stomach upset, and digestive system upset. It can also cause itching, rash, and allergic reactions, particularly in people allergic to aspirin.
Warnings & Precautions
- Pregnancy: There isn’t enough reliable information to know if this extract 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 the 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 in 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: This extract 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 the bark. Using this extract might cause serious allergic reactions. Avoid use.
- Surgery: This extract 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.
Dosage Of Willow Bark
The following doses have been studied in scientific research:
For back pain: Willow bark extract providing 120-240 mg salicin has been used. The higher 240 mg dose might be more effective.
Consult your doctor or pharmacist.
All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.