American Wormseed (Dysphania ambrosioides, formerly Chenopodium ambrosioides) has a long history of traditional use as an anthelmintic, particularly for the treatment of intestinal parasites such as roundworms and hookworms. Historical records show that Native American populations and later European settlers in North America utilized the seeds and oil of this plant for expelling intestinal worms. The active compound, ascaridole, was identified as responsible for its anthelmintic properties. Wormseed oil was included in the U.S. Pharmacopeia in the 19th and early 20th centuries for this purpose.

However, while traditional use is well documented, scientific validation is limited. Some older clinical and laboratory studies from the early 20th century did show efficacy of wormseed oil against certain nematodes, but concerns about toxicity (including neurotoxicity and hepatotoxicity) led to its decline in medical use. Modern anthelmintic drugs with better safety profiles have replaced it. Recent scientific studies are sparse, and current clinical guidelines do not recommend American Wormseed due to safety concerns and lack of robust contemporary evidence.