Willow Bark is used to ease pain and reduce inflammation. Researchers believe that the chemical salicin, found in Willow Bark, is responsible for these effects. Studies have also identified several other components of Willow Bark that have fever-reducing properties. The bark of white willow contains salicin, which is a chemical similar to Aspirin (acetylsalicylic acid). Salicin is the main component responsible for the pain-relieving and anti-inflammatory effects of the herb, salicin was used to develop Aspirin.