Scientific Name: White Willow
Other Names: Basket Willow, Crack Willow, Salix, Salix alba, Salix fragilis, Salix purpurea

Who is this for?

Uses

White willow bark was the original source of aspirin. Although most modern aspirin products are synthetic, white willow products contain some of the same chemicals that are in aspirin--specifically salicin and other chemicals that belong to the salicylates group of drugs. These chemicals are anti-inflammatory, which means that they help to reduce the swelling and pain that results from infection, injury, or irritation. Therefore, white willow may provide mild relief for arthritis, back pain, headache, and other types of pain. In addition, salicylates may give white willow limited ability to reduce fever. A very small study of patients with migraine headaches found that a combination product containing feverfew and white willow helped to prevent migraines and also lessened the severity and length of migraines that did occur. In general, however, the effects of white willow are milder than those from aspirin; and, unlike aspirin, white willow may take up to one week of continual use to reach an effective level of pain relief.

White willow products contain a relatively high percentage of tannins, a group of chemicals that have been associated with kidney or liver damage. Therefore, individuals who have kidney or liver conditions should avoid using white willow because it may worsen those conditions.

Because individuals who are allergic to aspirin may also be allergic to white willow, they should not take products containing white willow or salicin.

For reasons that are unclear, many individuals who have asthma also have aspirin allergies or sensitivities. Since white willow contains many of the same chemicals as aspirin, white willow should not be taken by individuals with asthma.

Individuals who have hemophilia or other disorders of blood clotting should avoid taking white willow because the salicylates in white willow possibly may interfere with blood clotting.

Due to the possibility that tannins and other chemicals in white willow may irritate the lower gastrointestinal tract, individuals with stomach ulcers or inflammatory bowel diseases should not use it.

White willow should not be given to children due to the chance it may cause a rare but serious condition called Reye's syndrome. Usually occurring after a viral illness such as chicken pox or flu has been treated with aspirin, Reye's syndrome may have early symptoms such as confusion, prolonged vomiting, and rapid breathing. Coma may result, if immediate treatment is not provided.

Precautions

Cases of rash have been documented in infants whose mothers used white willow while breastfeeding. While no severe results have been reported, the use of white willow is not recommended during breastfeeding.

Not enough is known about how white willow might affect a developing infant to recommend its use during pregnancy.

What side effects should I watch for?

Major Side Effects

Although few side effects have been reported from the oral use of white willow, products that contain aspirin or tannins may possibly cause kidney, liver, or stomach damage--especially when taken in high doses or for extended periods.

A case study has been published concerning several people who regularly used large amounts of an oral product containing tannins comparable to those in white willow for many years. Generally, this group had a higher incidence of tongue and lip cancer than expected. Cancers of the nose and esophagus may also be more likely in people who take large amounts of tannin-containing products for a long time.

Less Severe Side Effects

Because white willow contains some of the same chemicals that are in aspirin, they both may cause similar side effects, such as:

• Blood in the stool
• Nausea
• Ringing in the ears
• Upset stomach
• Vomiting

Rarely, applying white willow to the skin or handling the fresh or dried bark may cause a rash.

What interactions should I watch for?

The tannin content of white willow products may interfere with the way that prescription drugs such as theophylline and codeine, non-prescription drugs such as pseudoephedrine, dietary supplements such as iron, and some foods are used by the body. Individuals who take drugs or other supplements and white willow should allow as much time as possible (at least 2 hours) between taking the white willow and taking the other drugs.

Prescription Drugs

The salicylates in white willow may increase the time blood needs to clot. When it is taken with antiplatelet or anticoagulant drugs, the effect of the drug may be increased, resulting in uncontrolled bleeding.

• Antiplatelets include clopidogrel and Ticlid
• Anticoagulants include heparin and warfarin

Aspirin may lower blood sugar levels slightly. If it is taken at the same time as a drug from the sulfonylurea group that is used to treat diabetes, blood sugar levels may get too low. Since white willow has some of the same chemicals as aspirin, it may also increase the effectiveness of sulfonylureas, which include:

• glimepiride
• glipizide
• glyburide
• Glyset

Although no reports of a similar interaction have been reported with white willow, aspirin may reduce the effectiveness of beta blockers, drugs used to decrease high blood pressure and treat other heart conditions. Beta blockers include:

• atenolol
• metoprolol
• propranolol

Non-prescription Drugs

If white willow is taken at the same time aspirin is taken, the effects of aspirin and the potential for side effects may both increase. Additionally, white willow can decrease the ability of blood to clot after an injury. Aspirin can also delay clotting, so white willow should not be taken orally at the same time as aspirin.

Herbal Products

Certain other herbal products, such as black cohosh and wintergreen, also contain salicylates. If one of these products is taken with white willow, the amounts of salicylates in the blood may increase, possibly increasing the risk of side effects.

Theoretically, if white willow is used with other herbs that affect blood clotting, bleeding may occur. Some of the most common herbal products that might inhibit blood clotting are:

• Danshen
• Devil's Claw
• Eleuthero
• Garlic
• Ginger (in high amounts)
• Gingko
• Horse Chestnut
• Panax Ginseng
• Papain
• Red Clover
• Saw Palmetto

Foods

If aspirin and alcohol are used together, the chances of stomach upset or damage to the stomach lining may increase. White willow may also cause the body to absorb alcohol faster--potentially leading to physical or mental impairment or even intoxication more quickly than expected, even with relatively low amounts of alcohol consumption.

Additionally, the tannins in white willow may interfere with the absorption of iron and other minerals from foods. A dietary deficiency of these minerals is very rare in the United States, but taking large amounts of white willow may result in less mineral absorption from foods.

Some interactions between herbal products and medications can be more severe than others. The best way for you to avoid harmful interactions is to tell your doctor and/or pharmacist what medications you are currently taking, including any over-the-counter products, vitamins, and herbals. For specific information on how white willow interacts with drugs, other herbals, and foods and the severity of those interactions, please use our Drug Interactions Checker to check for possible interactions.

Should I take it?

Many species of willow trees grow mostly in countries with moderate or cool climates. They grow faster than most other trees, they are relatively easy to plant from cuttings, and they can be planted close together--making them popular for hedge rows and wind breaks. Familiar sights along riverbanks, near swamps, and in other wet areas, willows are often planted to help prevent soil erosion. In recent years, they have been found to take up environmental pollutants such as iron cyanide and zinc from the ground and water at contaminated industrial sites. The trees do not store the contaminants, but break them up and release them as less harmful substances, without apparent damage to the trees.

Willows are easily recognized by their long, flexible, leaf-covered branches that are called rods or whips. For centuries, willow whips have been used to make baskets. Willow wood has also been used for furniture and ornamental fences. In the United Kingdom, it is the traditional material for cricket bats. Willow wood is also used to make charcoal.

For use as medicine, bark is removed from woody branches that are between 2 years and 4 years old. White willow bark is harvested in the spring before the trees flower. While all willows contain some amounts of the same main chemicals, some species have much higher concentrations of one component or another.

Dosage and Administration

White willow is available in several dosage forms, including liquid extracts and tinctures, to be taken by mouth. Extracts are concentrated liquid preparations usually made by soaking chopped or mashed plant parts in a liquid such as alcohol, and then straining out the solid parts. Tinctures are less concentrated than extracts, but they are prepared in similar ways. Many white willow products are standardized according to their content of salicin. Standardization by the manufacturer should assure the same amount of active ingredient in every batch of the commercial preparation. Standardization of herbal products is not required by the U.S. Food and Drug Administration (FDA), so not every product will contain the same amounts of active ingredients.

A typical daily dose of salicin is 60 mg to 120 mg. In some studies, doses up to 240 mg per day have been used without apparent side effects. If dried white willow bark is used, it may be brewed into a tea by pouring about 5 ounces of boiling water over 1,000 mg to 3,000 mg (one gram to 3 grams) of shredded white willow bark and letting it soak for 5 minutes before straining out the solid particles and drinking the tea. Because the salicin content of white willow bark varies widely, the exact amounts of active ingredients in each cup of white willow tea cannot be measured. Since much more or much less salicin may be in white willow bark than in standardized forms of white willow, tea made from white willow bark should be limited to three cups or less per day.

Summary

White willow may be useful for relieving pain and reducing fever. However, its effects are not as strong as aspirin's and it may not reach its full effectiveness until it is taken continually for a week or more.

Risks

Pregnant and breast-feeding women should avoid using white willow. Taking white willow may prompt an allergic response in individuals who are allergic to aspirin or who have asthma. Due to its content of salicylates (chemicals also in aspirin), white willow should not be used by children or by individuals with:

• Bleeding disorders
• Gastrointestinal diseases
• Kidney or liver conditions

Side Effects

Tannins, such as those contained in white willow, may be associated with kidney, liver, or stomach damage. Certain oral cancers may be more common in individuals who take large amounts of tannin-containing products for a long time. Common side effects of aspirin, which is similar to but stronger than white willow, may include:

• Blood in the stool
• Nausea
• Rash
• Ringing in the ears

Interactions

Tannins in white willow may block the absorption of drugs and foods from the gastrointestinal tract. In addition, white willow may increase the effects and side effects of other products, such as aspirin, that contain salicylates. White willow may also interfere with some of the same drugs, herbals, and foods that interact with aspirin. These products include:

• Alcohol
• Anticoagulants
• Antiplatelet agents
• Beta blockers
• Sulfonylurea agents for diabetes

In addition, white willow may increase the effects and side effects of other products, such as aspirin, that contain salicylates.

Last Revised April 18, 2008

References

Abebe W. Herbal medication: potential for adverse interactions with analgesic drugs. Journal of Clinical Pharmacy and Therapeutics. 2002;27(6):391-401.

Anon: Willow bark. In: DerMarderosian A, Beutler JA, eds. Facts and Comparisons: The Review of Natural Products. St. Louis, MO, Facts and Comparisons. March 2000.

Boullata JI, McDonnell PJ, Oliva CD. Anaphylactic reaction to a dietary supplement containing willow bark. Annals of Pharmacotherapy. 2003;37(6):832-835.

Chrubasik S, Eisenberg E, Balan E, Weinberger T, Luzzati R, Conradt C. Treatment of low back pain exacerbations with willow bark extract: a randomized double-blind study. American Journal of Medicine. 2000;109(1):9-14.

Chrubasik S, Kunzel O, Model A, Conradt C, Black A. Treatment of low back pain with a [sic] herbal or synthetic anti-rheumatic: a randomized controlled study. Willow bark extract for low back pain. Rheumatology (Oxford). 2001;40(12):1388-1393.

Chrubasik S, Pollak S. Pain management with herbal antirheumatic drugs. [article in German] Wiener Medizinische Wochenschrift. 2002;152(7-8):198-203.

Clauson KA, Santamarina ML, Buettner CM, Cauffield JS. Evaluation of presence of aspirin-related warnings with willow bark. Annals of Pharmacotherapy. 2005;39(7-8):1234-1237.

D'Acquisto F, Ianaro A. From willow bark to peptides: the ever widening spectrum of NF-kappaB inhibitors. Current Opinion on Pharmacology. 2006;6(4):387-392.

French CJ, Dickinson NM, Putwain PD. Woody biomass phytoremediation of contaminated brownfield land. Environmental Pollution. 2006;141(3):387-395.

Gagnier JJ, van Tulder MW, Berman B, Bombardier C. Herbal medicine for low back pain: a Cochrane review. Spine. 2007;32(1):82-92.

Gagnier J, Vantulder M, Berman B, Bombardier C. Herbal medicine for low back pain. Cochrane Database Systematic Review. April 19, 2006;(2):CD004504.

Heck AM, DeWitt BA, Lukes AL. Potential interactions between alternative therapies and warfarin. American Journal of Health System Pharmacy. 2000;57(13):1221-1227 and1228-1230.

Hedner T, Everts B. The early clinical history of salicylates in rheumatology and pain. Clinical Rheumatology. 1998;17(1):17-25.

Jellin JM, Gregory P, Batz F, Hitchens K, et al, eds. Pharmacist's Letter/Prescriber's Letter. Natural Medicines Comprehensive Database, 3rd Edition. Stockton CA: Therapeutic Research Facility, 2000.

Kammerer B, Kahlich R, Biegert C, Gleiter CH, Heide L. HPLC-MS/MS analysis of willow bark extracts contained in pharmaceutical preparations. Phytochemical Analysis. 2005;16(6):470-478.

Khayyal MT, El-Ghazaly MA, Abdallah DM, Okpanyi SN, Kelber O, Weiser D. Mechanisms involved in the anti-inflammatory effect of a standardized willow bark extract. Arzneimittelforschung. 2005;55(11):677-687.

Krivoy N, Pavlotzky E, Chrubasik S, Eisenberg E, Brook G. Effect of salicis cortex extract on human platelet aggregation. Planta Medica. 2001;67(3):209-212.

Lafont O. From the willow to aspirin. [Article in French] Rev Hist Pharm (Paris). 2007;55(354):209-216.

Larsen M, Trapp S. Uptake of iron cyanide complexes into willow trees. Environmental Science and Technology. 2006;40(6):1956-1961.

Marz RW, Kemper F. Willow bark extract--effects and effectiveness. Status of current knowledge regarding pharmacology, toxicology and clinical aspects. [article in German] Wiener Medizinische Wochenschrift. 2002;152(15-16):354-359.

McCurdy CR, Scully SS. Analgesic substances derived from natural products (natureceuticals). Life Sciences. 2005;78(5):476-484.

Morgenson G. 1992. Vegetative propagation of poplar and willow. In: Landis, T.D., technical coordinator. Proceedings, Intermountain Forest Nursery Association; 1991 August 12-16; Park City, UT. General Technical Report RM-211. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 84-86. Available at: http://www.sernw.org/d2d_2005_docs/Workshop_3/Cuttings_Bioengineering_in_Restoration/USDA%20willow%20pop%20prop.pdf. Accessed June 22, 2006.

Mueller RL, Scheidt S. History of drugs for thrombotic disease. Discovery, development, and directions for the future. Circulation. 1994;89(1):432-449.

Natural Medicines Comprehensive Database, Online Edition. Pharmacist's Letter/Prescriber's Letter. Stockton CA: Therapeutic Research Facility, 2006. Available at: http://www.pharmacistsletter.com/(S(ulqz3s45omt3ag55um4kj345))/home.aspx?li=1&st=1&cs=&s=ND.

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. Phytotherapy Research. 2001;15(4):344-350.

Setty AR, Sigal LH. Herbal medications commonly used in the practice of rheumatology: mechanisms of action, efficacy, and side effects. Seminars in Arthritis and Rheumatism. 2005;34(6):773-784.

Sharpe PA, Granner ML, Conway JM, Ainsworth BE, Dobre M. Availability of weight-loss supplements: Results of an audit of retail outlets in a southeastern city. Journal of the American Dietetic Association. 2006;106(12):2045-2051.

Shrivastava R, Pechadre JC, John GW. Tanacetum parthenium and Salix alba (Mig-RL) combination in migraine prophylaxis: a prospective, open-label study. Clinical Drug Investigation. 2006;26(5):287-296.

Vainio H, Morgan G. Aspirin for the second hundred years: new uses for an old drug. Pharmacology and Toxicology. 1997;81(4):151-152.

Weber RW. White willow. Annals of Allergy, Asthma and Immunology. 2004;92(2):A6.

Yu XZ, Gu JD. Uptake, metabolism, and toxicity of methyl tert-butyl ether (MTBE) in weeping willows. Journal of Hazardous Materials. Epublished ahead of print April 25, 2006.

Yu XZ, Zhou PH, Yang YM. The potential for phytoremediation of iron cyanide complex by willows. Ecotoxicology. Epublished ahead of print May 16, 2006.

Last Revised April 18, 2008

Note: The above information is not intended to replace the advice of your physician, pharmacist, or other healthcare professional. It is not meant to indicate that the use of the product is safe, appropriate, or effective for you.

In general, herbal products are not subject to review or approval by the U.S. Food and Drug Administration (FDA). They are not required to be standardized, meaning that the amounts of active ingredients or contaminants they contain may vary between brands or between different batches of the same brand. Not all of the risks, side effects, or interactions associated with the use of herbal products are known because few reliable studies of their use in humans have been done.

This information is provided for your education only. Please share this information with your healthcare provider and be sure that you talk to your doctor and pharmacist about all the prescription and non-prescription medicines you take before you begin to use any herbal product.

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