Benznidazole is an antibiotic that is used to treat a certain parasitic infection (Chagas disease). It works by stopping the growth of a certain parasite. This antibiotic treats only Chagas disease. It will not work for viral infections (such as common cold, flu). Using any antibiotic when it is not needed can cause it to not work for future infections. It is used treat an infection called American trypanosomiasis (Chagas disease) in children 2 to 12 years of age. It is an oral tablet taken for 60 days. Benznidazole belongs to a group of drugs called antiprotozoals. Common side effects of benznidazole include abdominal pain, rash, and decreased weight.