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