Molecular Formula: C13H18O7 Molecular Mass: 286.29 White willow extract CAS No.: 138-52-3 Because white willow bark contains salicylates, the same precautions as aspirin should be taken until research has shown otherwise. The following people should not take white willow bark:People with an aspirin allergy or sensitivity. There has been a published report of a 25 year old woman who was admitted ...