Croton oil (Crotonis Oleum) is an oil prepared from the seeds of Croton tiglium, a tree belonging to the natural order Euphorbiales and family Euphorbiaceae, and native or cultivated in India and the Malay Archipelago. Small doses taken internally cause diarrhea. Externally, the oil can cause irritation and swelling. In traditional Chinese medicine it is used as an ingredient in some liniments.
The ancient Chinese were the first to use croton oil as a medicine. In the late 16th century, European merchants brought the oil to Europe from the east. Its main uses were as a purgative and counter-irritant. Croton oil’s powerful toxic effects eventually caused it to fall out of favor with most medical practitioners. In the 1920s, phenol-croton oil peels became a popular skin-care fad.