药鼠李（学名：Rhamnus cathartica）为鼠李科鼠李属下的一个种。

可当作一种结肠的清洁剂及通便剂，对结肠障碍、便秘以及寄生虫感染很有效。当成茶来服用时，味道非常苦。

Rhamnus cathartica (buckthorn, common buckthorn or purging buckthorn) is a species of small tree in the flowering plant family Rhamnaceae. It is native to Europe, northwest Africa and western Asia, from the central British Isles south to Morocco, and east to Kyrgyzstan. It was introduced to North America as an ornamental shrub in the early 19th century or perhaps before.