Sources: Willow is the inner bark of several species of Salix, trees in the willow family, including white willow (S. alba), crack willow (S. fragilis), purple willow (S. purpurea), violet willow (S. daphnoides), and bay willow (S. pentandra). All but bay willow are naturalized in North America.

Traditional Use: For more than 2,000 years, people of the northern hemisphere used willow bark as a wash for external ulcers and internally to reduce fevers and relieve aches, pains, rheumatism, arthritis, and headaches. The Houma used black willow root bark as a blood thinner; the Creek used the root tea to relieve inflammation in rheumatism and reduce fever. In American folk tradition, the bark was used to thin the blood and treat fever. The tea was also taken for dyspepsia. In 1763, a Dr. Stone of London first recommended willow bark to the medical profession for the treatment of fevers.

Current Use: In the 1890s the Bayer Company was looking for a substitute for wintergreen and black birch oil, then used to relieve pain, because the substances were simply too toxic. While studying experiments from 1853 in which salicylic acid was first synthesized from carbolic acid, Bayer researchers synthesized a derivative, acetylsalicylic acid, commonly known today as aspirin. No other drug is as well-known for its analgesic, fever-reducing, or anti-inflammatory qualities. Willow bark is considered a "natural aspirin."

Willow bark compounds are oxidized in the liver and blood to produce salicylic acid. It has pain-relieving effects like aspirin, but with fewer side effects. But can you take enough willow bark to achieve the effect of aspirin? According to Varro Tyler, probably not.

AT-A-GLANCE

Used For: Aches and pains * Fever Preparations: Dried bark, whole, cut and sifted, powdered; capsules, tablets, tea. European products are standardized to 1% salicin. Typical Dosages: Capsules: Up to six 400 mg capsules a day. Tea: Steep 1/4-1/2 tsp powdered bark in 1 cup hot water for 10-15 minutes. Taken 3 times a day, this might not deliver more than 120 mg salicin-far less than a dose of aspirin. Or follow manufacturer's or practitioner's recommendations. Cautions: Willow bark is high in tannins, which can damage the liver. Because willow bark produces salicin, it is contraindicated in the same instances as aspirin for stomach ulcers and, in children, for high fever.

References

Willow References: Julkunen-Tiitto, R. and B. Meier. 1992. "The Enzymatic Decomposition of Salicin and Its Derivatives Obtained from Salicaceae Species." Journal of Natural Products 55(9):1204-12.

Tyler, V. and S. Foster. 1996. "Herbs and Phytomedicines." In Handbook of Nonprescription Drugs (11th ed.). Washington, DC: The American Pharmaceutical Association.