Willow

Common name: Willow bark

Botanical name: Salix alba

Parts used and where grown

The willow tree grows primarily in central and southern Europe, although it is also found in North America. The bark is used to make herbal extracts.

Willow has been used in connection with the following conditions (refer to the individual health concern for complete information):

Science Ratings

Health Concerns

Fever

Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars

Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star

For a herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

Historical or traditional use (may or may not be supported by scientific studies)

Willow bark was used traditionally by herbalists for fever, headache, pain, and rheumatic complaints.¹ In the late 19th century, the constituent salicylic acid was isolated from willow bark and went on to become the model for the development of aspirin (acetylsalicylic acid).²

Active constituents

The glycoside salicin, from which the body can split off salicylic acid, is thought to be the source of the anti-inflammatory and pain-relieving actions of willow.³ The analgesic actions of willow are typically slow to develop but may last longer than the effects of standard aspirin products. One trial has found that a combination herbal product including 100 mg willow bark taken for two months improved functioning via pain relief in people with osteoarthritis.⁴ Another trial found that 1360 mg of willow bark extract per day (delivering 240 mg of salicin) for two weeks was somewhat effective in treating pain associated with knee and/or hip osteoarthritis.⁵ Use of high amounts of willow bark extract may also help people with low back pain. One four-week trial found 240 mg of salicin from a willow extract was effective in reducing exacerbations of low back pain.⁶

How much is usually taken?

Willow extracts standardised for salicin content are available. The commonly recommended intake of salicin has been 60–120 mg per day.⁷ However, newer studies suggest a higher salicin intake of 240 mg per day may be more effective for treating pain.⁸ A willow tea can be prepared from 1/4–1/2 teaspoon (1–2 grams) of bark boiled in about 7 ounces (200 ml) of water for ten minutes. Five or more cups (1250 ml) of this tea can be drunk per day. Tincture, 1–1 1/2 teaspoons (5–8 ml) three times per day, is also occasionally used.

Are there any side effects or interactions?

As with aspirin, some people may experience stomach upset from taking willow. Although such symptoms are less likely from willow than from aspirin, people with ulcers and gastritis should, nevertheless, avoid this herb.⁹ Again, as with aspirin, willow should not be used to treat fevers in children since it may cause Reye’s syndrome.

Are there any drug interactions?
Certain medicines may interact with willow. Refer to drug interactions for a list of those medicines.

References
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1. Weiss RF. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum, 1988, 31, 303.

2. Foster S. 101 Medicinal Herbs. Loveland, CO: Interweave Press, 1998, 210–1.

3. Bradley PR (ed). British Herbal Compendium, vol 1. Bournemouth, Dorset, UK: British Herbal Medicine Association, 1992, 224–6.

4. 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 Rheum 1996;35:874–8.

5. Schmid B, Tschirdewahn B, Kàtter I, et al. Analgesic effects of willow bark extract in osteoarthritis: results of a clinical double-blind trial. Fact 1998;3:186.

6. 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.

7. Blumenthal M, Busse WR, Goldberg A, et al. (eds). The Complete Commission E Monographs: Therapeutic Guide to Herbal Medicines. Boston, MA: Integrative Medicine Communications, 1998, 230.

8. 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.

9. Blumenthal M, Busse WR, Goldberg A, et al. (eds). The Complete Commission E Monographs: Therapeutic Guide to Herbal Medicines. Boston, MA: Integrative Medicine Communications, 1998, 230.

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires March 2007.