Anodyne, antiseptic, astringent, diaphoretic, diuretic, febrifuge, tonic. The ability of willow bark to alleviate pain and reduce fever has been known for at least two thousand years. It contains salicin, a glycoside that is converted to salicylic acid in the body. Salicylic acid is closely related to aspirin, the synthetic drug that has displaced willow bark from popular use. Willow bark reduces inflammation and makes an effective treatment for articular rheumatism.