A systematic review on the effectiveness of willow bark for musculoskeletal pain

Since ancient times preparations from Salix species have been used to alleviate pain. The aim of this study was to update the evidence of the effectiveness of willow bark products in the treatment of musculoskeletal pain. OVID(MEDLINE), PUBMED, Silverplatter, and CENTRAL and manual searches were used to identify clinical trials investigating Salix preparations. Authors SC and JEV extracted the data independently and discussed disagreements. Seven manuscripts were identified, reporting four trials with confirmatory and four with exploratory study designs. Three manuscripts presented the same trial data: repetitious reports were excluded. One confirmatory and two exploratory studies indicate a dose-dependent analgesic effect not inferior to rofecoxib in patients with low back pain. In one exploratory and one confirmatory study conflicting results were achieved in participants with osteoarthritis. No significant effect was seen in a confirmatory study in patients with rheumatoid arthritis, but this study was grossly underpowered. All studies investigated ethanolic extracts with daily doses up to 240 mg salicin over periods of up to six weeks. Minor adverse events occurred during treatment. The review provides moderate evidence of effectiveness for the use of ethanolic willow bark extract in low back pain. Further studies are required to find out if treatment of osteoarthritis and rheumatoid arthritis requires extract with higher doses than 240 mg salicin per day.