Just to be clear: There is no aspirin in willow bark. Willow bark contains salicin which metabolizes into salicylic acid (which is still different from aspirin, ie. acetylsalicylic acid).
I could be wrong, but isn't that the main ingredient in Stridex? I used to have oily skin (before changing my diet) and I could've sworn that I used salicylic acid as a chemical exfoliant.