Levamisole hydrochloride (Ergamisol®) is an antibiotic medication used in combination with fluorouracil to treat colon cancer.

Levamisole is a synthetic imidazothiazole derivative, and was originally used as an antihelminthic to treat worm infestations in both humans and animals. Its mechanism of action in treating colon cancer is unclear, although it has been shown to have immune-stimulating properties. It is also used infrequently to treat melanoma and head and neck cancer.

Levamisole is given orally, and is metabolized primarily by the liver.