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Willow Bark

What is it?

Willow bark is the bark from several varieties of the willow tree, including white willow or European willow, black willow or pussy willow, crack willow, purple willow, and others. The bark is used to make medicine.

Willow bark acts a lot like aspirin, so it is used for pain, including headache, muscle or joint pain, menstrual cramps, rheumatoid arthritis (RA), osteoarthritis, gout, and a disease of the spine called ankylosing spondylitis.

Willow bark's pain relieving potential has been recognized throughout history. Willow bark was commonly used during the time of Hippocrates, when people were advised to chew on the bark to relieve pain and fever.

Willow bark is also used for the common cold, flu, and weight loss.

Salicin, the active ingredient in willow bark, seems to have contributed to the death of the composer, Ludwig von Beethoven. Apparently, Beethoven ingested large amounts of salicin before he died. His autopsy report is the first recorded case of a particular type of kidney damage that can be caused by salicin.

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...

  • Treating lower 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 in symptoms.

Insufficient evidence to rate effectiveness for...

  • Joint pain. Research shows that taking a specific product containing glucosamine sulfate, methylsufonlylmethane, white willow bark extract, ginger root concentrate, boswellia extract, turmeric root extract, cayenne, and hyaluronic acid (Instaflex Joint Support, Direct Digital, Charlotte, NC) in three divided doses daily for 8 weeks reduces joint pain. But this product doesn't seem to help joint stiffness or function.
  • Weight loss. Early research suggests that taking willow bark in combination with ephedra and cola nut might cause slight weight loss in overweight and obese people. However, 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 rheumatoid arthritis.
  • Joint pain.
  • Treating fever.
  • Other conditions.
More evidence is needed to rate the effectiveness of willow bark for these uses.

How does it work?

Willow bark contains a chemical called salicin that is similar to aspirin.

Are there safety concerns?

Willow bark is POSSIBLY SAFE for most people when taken by mouth for a short time (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.

Special precautions & warnings:

Pregnancy and breast-feeding: Not enough is known about the safety of using willow bark during pregnancy. It's best to avoid using it.

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, which might lead to kidney failure in certain 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?

Major
Do not take this combination.
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.
Moderate
Be cautious with this combination.
Acetazolamide
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.
Aspirin
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 an aspirin-like chemical (Salicylate)
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?

The following doses have been studied in scientific research:

BY MOUTH:
  • For back pain: Willow bark extract providing 120-240 mg salicin has been used. The higher 240 mg dose might be more effective.

Other names

Basket Willow, Bay Willow, Black Willow, Black Willow Extract, Brittle Willow, Corteza de Sauce, Crack Willow, Daphne Willow, Écorce de Saule, Écorce de Saule Blanc, European Willow, European Willow Bark, Extrait d'Écorce de Saule, Extrait d'Écorce de Saule Blanc, Extrait de Saule, Extrait de Saule Blanc, Knackweide, Laurel Willow, Lorbeerweide, Organic Willow, Osier Blanc, Osier Rouge, Purple Osier, Purple Osier Willow, Purple Willow, Purpurweide, Pussy Willow, Reifweide, Salicis Cortex, Salix alba, Salix daphnoides, Salix fragilis, Salix nigra, Salix pentandra, Salix purpurea, Saule, Saule Argenté, Saule Blanc, Saule Commun, Saule des Viviers, Saule Discolore, Saule Fragile, Saule Noir, Saule Pourpre, Silberweide, Violet Willow, Weidenrinde, White Willow, White Willow Bark, Willowbark, White Willow Extract, Willow Bark Extract.

Methodology

To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.

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Last reviewed - 08/16/2018