Oxamniquine, sold under the brand name Vansil among others, is a medication used to treat schistosomiasis due to Schistosoma mansoni. Praziquantel, however, is often the preferred treatment. It is given by mouth and used as a single dose.

Common side effects include sleepiness, headache, nausea, diarrhea, and reddish urine. It is typically not recommended during pregnancy, if possible. Seizures may occur and therefore caution is recommended in people with epilepsy. It works by causing paralysis of the parasitic worms. It is in the anthelmintic family of medications.

Oxamniquine was first used medically in 1972. It is on the World Health Organization's List of Essential Medicines. It is not commercially available in the United States. It is more expensive than praziquantel.