Bismuth subsalicylate contains salicylates. Various herbs including meadowsweet (Filipendula ulmaria), poplar (Populus tremuloides),willow (Salix alba), and wintergreen (Gaultheria procumbens) contain salicylates as well. Though similar to aspirin, plant salicylates have been shown to have different actions in test tube studies. Furthermore, salicylates are poorly absorbed and likely do not build up to levels sufficient to cause negative interactions that aspirin might. No reports have been published of negative interactions between salicylate-containing plants and aspirin or aspirin-containing drugs. Therefore concerns about combining salicylate-containing herbs remain theoretical, and the risk of causing problems appears to be low.