URL of this page: https://medlineplus.gov/druginfo/natural/955.html

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 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 fever, 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...

  • 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 suggests it can reduce osteoarthritis pain, while other research shows no effect.
  • Rheumatoid arthritis (RA). Early research suggests that willow bark extract is not effective for rheumatoid arthritis.
  • Treating fever.
  • Joint pain.
  • 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 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 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.

References

  1. Gagnier JJ, VanTulder MW, Berman B, and et al. Botanical medicine for low back pain: a systematic review [abstract]. 9th Annual Symposium on Complementary Health Care, December 4th-6th, Exter, UK 2002.
  2. Werner G, Marz RW, and Schremmer D. Assalix for chronic lower back pain and arthralgia: interim analysis of a post marketing surveillance study. 8th Annual Symposium on Complementary Health Care, 6th - 8th December 2001 2001.
  3. Little CV, Parsons T, and Logan S. Herbal therapy for treating osteoarthritis. The Cochrane Library 2002;1.
  4. Meier B, Sticher O, and Bettschart A. Quality control of willow bark: quantitative analysis of total salicin in willow bark and willow preparations with HPLC. Deutsche Apotheker Zeitung 1985;125:341-347.
  5. Loniewski I, Glinko A, and Samochowiec L. Standardised willow bark extract: a potent anti-inflammatory drug . 8th Annual Symposium on Complementary Health Care, 6th-8th December 2001 2001.
  6. Dabrowska-Zamojcin EI, Glinko A, Samochowiec L, and et al. Willow bark extract and aspirin, their potential for gastric injury in mice and other toxicity aspects. 8th Annual Symposium on Complementary Health Care, 6th-8th December 2001 2001.
  7. Schaffner W. Eidenrinde-ein antiarrheumatikum der modernen Phytotherapie? 1997;125-127.
  8. Black A, Künzel O, Chrubasik S, and et al. Economics of using willow bark extract in outpatient treatment of low back pain [abstract]. 8th Annual Symposium on Complementary Health Care, 6th-8th December 2001 2001.
  9. Chrubasik S, Künzel O, Model A, and et al. Assalix® vs. Vioxx® for low back pain - a randomised open controlled study. 8th Annual Symposium on Complementary Health Care, 6th - 8th December 2001 2001.
  10. Meier B, Shao Y, Julkunen-Tiitto R, and et al. A chemotaxonomic survey of phenolic compounds in Swiss willow species. Planta Medica 1992;58(suppl 1):A698.
  11. Hyson MI. Anticephalgic photoprotective premedicated mask. A report of a successful double-blind placebo-controlled study of a new treatment for headaches with associated frontalis pain and photophobia. Headache 1998;38:475-477.
  12. Rohnert, U., Schneider, W., and Elstner, E. F. Superoxide-dependent and -independent nitrite formation from hydroxylamine: inhibition by plant extracts. Z Naturforsch.[C.] 1998;53(3-4):241-249. View abstract.
  13. Hogstad, O. Accumulation of cadmium, copper and zinc in the liver of some passerine species wintering in central Norway. Sci Total Environ. 4-26-1996;183:187-194. View abstract.
  14. Steinegger, E. and Hovel, H. [Analytic and biologic studies on Salicaceae substances, expecially on salicin. II. Biological study]. Pharm Acta Helv. 1972;47:222-234. View abstract.
  15. Sweeney, K. R., Chapron, D. J., Brandt, J. L., Gomolin, I. H., Feig, P. U., and Kramer, P. A. Toxic interaction between acetazolamide and salicylate: case reports and a pharmacokinetic explanation. Clin Pharmacol Ther 1986;40:518-524. View abstract.
  16. Baker, S. and Thomas, P. S. Herbal medicine precipitating massive haemolysis. Lancet 5-2-1987;1:1039-1040. View abstract.
  17. Fotsch, G. and Pfeifer, S. [The biotransformation of leiocarposide and salicin phenol glycosides-- examples for special consideration of the absorption and metabolism of glycosidic compounds]. Pharmazie 1989;44:710-712. View abstract.
  18. Wick JY. Aspirin: a history, a love story. Consult Pharm. 2012 May;27:322-9.

    View abstract.
  19. Moro PA, Flacco V, Cassetti F, Clementi V, Colombo ML, Chiesa GM, Menniti-Ippolito F, Raschetti R, Santuccio C. Hypovolemic shock due to severe gastrointestinal bleeding in a child taking an herbal syrup. Ann Ist Super Sanita. 2011;47:278-83.

    View abstract.
  20. Kim JB, Kim JM, Kim SY, Kim JH, Park YB, Choi NJ, Oh DH. Comparison of enterotoxin production and phenotypic characteristics between emetic and enterotoxic Bacillus cereus. J Food Prot. 2010 Jul;73:1219-24. 

    View abstract.
  21. Cameron, M., Gagnier, J. J., Little, C. V., Parsons, T. J., Blumle, A., and Chrubasik, S. Evidence of effectiveness of herbal medicinal products in the treatment of arthritis. Part I: Osteoarthritis. Phytother.Res 2009;23:1497-1515. View abstract.
  22. Kenstaviciene P, Nenortiene P, Kiliuviene G, Zevzikovas A, Lukosius A, Kazlauskiene D. Application of high-performance liquid chromatography for research of salicin in bark of different varieties of Salix. Medicina (Kaunas). 2009;45:644-51.

    View abstract.
  23. Vlachojannis JE, Cameron M, Chrubasik S. A systematic review on the effectiveness of willow bark for musculoskeletal pain. Phytother Res. 2009 Jul;23:897-900.

    View abstract.
  24. Rishton GM. Natural products as a robust source of new drugs and drug leads: past successes and present day issues. Am J Cardiol. 2008 May 22;101(10A):43D-49D.

    View abstract.
  25. Nahrstedt A, Schmidt M, Jäggi R, Metz J, Khayyal MT. Willow bark extract: the contribution of polyphenols to the overall effect. Wien Med Wochenschr. 2007;157(13-14):348-51.

    View abstract.
  26. D'Acquisto F, Ianaro A. From willow bark to peptides: the ever widening spectrum of NF-kappaB inhibitors. Curr Opin Pharmacol. 2006 Aug;6:387-92. Epub 2006 Jun 14.

    View abstract.
  27. Marson, P. and Pasero, G. [The Italian contributions to the history of salicylates]. Reumatismo. 2006;58:66-75. View abstract.
  28. Mahdi JG, Mahdi AJ, Mahdi AJ, Bowen ID. The historical analysis of aspirin discovery, its relation to the willow tree and antiproliferative and anticancer potential. Cell Prolif. 2006 Apr;39:147-55.

    View abstract.
  29. Khayyal, M. T., El Ghazaly, M. A., Abdallah, D. M., Okpanyi, S. N., Kelber, O., and Weiser, D. Mechanisms involved in the anti-inflammatory effect of a standardized willow bark extract. Arzneimittelforschung 2005;55:677-687. View abstract.
  30. Kammerer, B., Kahlich, R., Biegert, C., Gleiter, C. H., and Heide, L. HPLC-MS/MS analysis of willow bark extracts contained in pharmaceutical preparations. Phytochem Anal. 2005;16:470-478. View abstract.
  31. Meers, E., Lamsal, S., Vervaeke, P., Hopgood, M., Lust, N., and Tack, F. M. Availability of heavy metals for uptake by Salix viminalis on a moderately contaminated dredged sediment disposal site. Environ Pollut. 2005;137:354-364. View abstract.
  32. Clauson, K. A., Santamarina, M. L., Buettner, C. M., and Cauffield, J. S. Evaluation of presence of aspirin-related warnings with willow bark. Ann Pharmacother. 2005;39(7-8):1234-1237. View abstract.
  33. El Shemy, H. A., Aboul-Enein, A. M., Aboul-Enein, M. I., Issa, S. I., and Fujita, K. The effect of willow leaf extracts on human leukemic cells in vitro. J Biochem Mol Biol 7-31-2003;36:387-389. View abstract.
  34. Hammer, D. and Keller, C. Changes in the rhizosphere of metal-accumulating plants evidenced by chemical extractants. J Environ Qual. 2002;31:1561-1569. View abstract.
  35. Marz, R. W. and Kemper, F. [Willow bark extract--effects and effectiveness. Status of current knowledge regarding pharmacology, toxicology and clinical aspects]. Wien.Med.Wochenschr. 2002;152(15-16):354-359. View abstract.
  36. Akao, T., Yoshino, T., Kobashi, K., and Hattori, M. Evaluation of salicin as an antipyretic prodrug that does not cause gastric injury. Planta Med 2002;68:714-718. View abstract.
  37. Chrubasik, S., Kunzel, O., Black, A., Conradt, C., and Kerschbaumer, F. Potential economic impact of using a proprietary willow bark extract in outpatient treatment of low back pain: an open non-randomized study. Phytomedicine 2001;8:241-251. View abstract.
  38. Little CV, Parsons T. Herbal therapy for treating osteoarthritis. Cochrane Database Syst Rev. 2001;:CD002947.

    View abstract.
  39. Vane, J. R. The fight against rheumatism: from willow bark to COX-1 sparing drugs. J Physiol Pharmacol 2000;51(4 Pt 1):573-586. View abstract.
  40. Schmid, B., Ludtke, R., Selbmann, H. K., Kotter, I., Tschirdewahn, B., Schaffner, W., and Heide, L. [Effectiveness and tolerance of standardized willow bark extract in arthrosis patients. Randomized, placebo controlled double-blind study]. Z Rheumatol 2000;59:314-320. View abstract.
  41. Pass, G. J. and Foley, W. J. Plant secondary metabolites as mammalian feeding deterrents: separating the effects of the taste of salicin from its post-ingestive consequences in the common brushtail possum (Trichosurus vulpecula). J Comp Physiol [B] 2000;170:185-192. View abstract.
  42. Levesque, H. and Lafont, O. [Aspirin throughout the ages: a historical review]. Rev Med Interne 2000;21 Suppl 1:8s-17s. View abstract.
  43. Schmidt, U. Enhancing phytoextraction: the effect of chemical soil manipulation on mobility, plant accumulation, and leaching of heavy metals. J Environ Qual. 2003;32:1939-1954. View abstract.
  44. Rohner, Machler M., Glaus, T. M., and Reusch, C. E. [Life threatening intestinal bleeding in a Bearded Collie associated with a food supplement for horses]. Schweiz.Arch Tierheilkd. 2004;146:479-482. View abstract.
  45. Kahkonen, M. P., Hopia, A. I., Vuorela, H. J., Rauha, J. P., Pihlaja, K., Kujala, T. S., and Heinonen, M. Antioxidant activity of plant extracts containing phenolic compounds. J Agric.Food Chem 1999;47:3954-3962. View abstract.
  46. Chrubasik, J. E., Roufogalis, B. D., and Chrubasik, S. Evidence of effectiveness of herbal antiinflammatory drugs in the treatment of painful osteoarthritis and chronic low back pain. Phytother Res 2007;21:675-683. View abstract.
  47. Gagnier, J. J., van Tulder, M., Berman, B., and Bombardier, C. Herbal medicine for low back pain. Cochrane.Database.Syst.Rev. 2006;:CD004504. View abstract.
  48. Mills SY, Jacoby RK, Chacksfield M, Willoughby M. Effect of a proprietary herbal medicine on the relief of chronic arthritic pain: a double-blind study. Br J Rheumatol 1996;35:874-8. View abstract.
  49. Ernst, E. and Chrubasik, S. Phyto-anti-inflammatories. A systematic review of randomized, placebo-controlled, double-blind trials. Rheum.Dis Clin North Am 2000;26:13-27, vii. View abstract.
  50. Gagnier JJ, van Tulder MW, Berman B, Bombardier C. Herbal medicine for low back pain. A Cochrane review. Spine 2007;32:82-92. View abstract.
  51. Fiebich BL, Appel K. Anti-inflammatory effects of willow bark extract. Clin Pharmacol Ther 2003;74:96. View abstract.
  52. Coffey CS, Steiner D, Baker BA, Allison DB. A randomized double-blind placebo-controlled clinical trial of a product containing ephedrine, caffeine, and other ingredients from herbal sources for treatment of overweight and obesity in the absence of lifestyle treatment. Int J Obes Relat Metab Disord 2004;28:1411-9. View abstract.
  53. Krivoy N, Pavlotzky E, Chrubasik S, et al. Effect of salicis cortex extract on human platelet aggregation. Planta Med 2001;67:209-12. View abstract.
  54. Wagner I, Greim C, Laufer S, et al. Influence of willow bark extract on cyclooxygenase activity and on tumor necrosis factor alpha or interleukin 1 beta release in vitro and ex vivo. Clin Pharmacol Ther 2003;73:272-4. View abstract.
  55. Schmid B, Kotter I, Heide L. Pharmacokinetics of salicin after oral administration of a standardised willow bark extract. Eur J Clin Pharmacol. 2001;57:387-91. View abstract.
  56. Andreev E, Koopman M, Arisz L. A rise in plasma creatinine that is not a sign of renal failure: which drugs can be responsible? J Intern Med 1999;246:247-52. View abstract.
  57. Schwarz A. Beethoven's renal disease based on his autopsy: a case of papillary necrosis. Am J Kidney Dis 1993;21:643-52. View abstract.
  58. D'Agati V. Does aspirin cause acute or chronic renal failure in experimental animals and in humans? Am J Kidney Dis 1996;28:S24-9. View abstract.
  59. Chrubasik S, Kunzel O, Model A, et al. Treatment of low back pain with a herbal or synthetic anti-rheumatic: a randomized controlled study. Willow bark extract for low back pain. Rheumatology (Oxford) 2001;40:1388-93. View abstract.
  60. Clark JH, Wilson WG. A 16-day-old breast-fed infant with metabolic acidosis caused by salicylate. Clin Pediatr (Phila) 1981;20:53-4. View abstract.
  61. Unsworth J, d'Assis-Fonseca A, Beswick DT, Blake DR. Serum salicylate levels in a breast fed infant. Ann Rheum Dis 1987;46:638-9. View abstract.
  62. Food and Drug Administration, HHS. Labeling for oral and rectal over-the-counter drug products containing aspirin and nonaspirin salicylates; Reye's Syndrome warning. Final rule. Fed Regist 2003;68:18861-9. View abstract.
  63. Fiebich BL, Chrubasik S. Effects of an ethanolic salix extract on the release of selected inflammatory mediators in vitro. Phytomedicine 2004;11:135-8. View abstract.
  64. Biegert C, Wagner I, Ludtke R, et al. Efficacy and safety of willow bark extract in the treatment of osteoarthritis and rheumatoid arthritis: results of 2 randomized double-blind controlled trials. J Rheumatol 2004;31:2121-30. View abstract.
  65. Schmid B, Ludtke R, Selbmann HK, et al. Efficacy and tolerability of a standardized willow bark extract in patients with osteoarthritis: randomized placebo-controlled, double blind clinical trial. Phytother Res 2001;15:344-50. View abstract.
  66. Boullata JI, McDonnell PJ, Oliva CD. Anaphylactic reaction to a dietary supplement containing willow bark. Ann Pharmacother 2003;37:832-5.. View abstract.
  67. Food and Drug Administration, HHS. Final rule declaring dietary supplements containing ephedrine alkaloids adulterated because they present an unreasonable risk; Final rule. Fed Regist 2004;69:6787-6854. View abstract.
  68. Dulloo AG, Miller DS. Ephedrine, caffeine and aspirin: "over-the-counter" drugs that interact to stimulate thermogenesis in the obese. Nutrition 1989;5:7-9.
  69. Chrubasik S, Eisenberg E, Balan E, et al. Treatment of low back pain exacerbations with willow bark extract: a randomized double-blind study. Am J Med 2000;109:9-14. View abstract.
  70. Dulloo AG, Miller DS. Aspirin as a promoter of ephedrine-induced thermogenesis: potential use in the treatment of obesity. Am J Clin Nutr 1987;45:564-9. View abstract.
  71. Horton TJ, Geissler CA. Aspirin potentiates the effect of ephedrine on the thermogenic response to a meal in obese but not lean women. Int J Obes 1991;15:359-66. View abstract.
Last reviewed - 02/16/2015