... 15%, 25%,50%) Test Method:HPLC White Willow Bark ExtractIndications and UsageWhite Willow Bark contains salicin, which the body converts to ... pain. Native Americans also discovered the value of the Willow tree for relieving pain from headaches and rheumatism and reducing ... gastrointestinal disorder.As with aspirin products, never give white willow bark to children or teenagers under age 16 with symptoms ...