Nitazoxanide is a broad-spectrum antiparasitic and antiviral drug used to treat various helminthic, protozoal, and viral infections. It is indicated for the treatment of Cryptosporidium parvum and Giardia lamblia infections in immunocompetent patients, and for the treatment of influenza. Nitazoxanide has in vitro antiparasitic activity and clinical efficacy in the treatment of infections caused by other protozoa and helminths (e.g., Entamoeba histolytica, Hymenolepis nana, Ascaris lumbricoides, Cyclospora cayetanensis). There is evidence that nitazoxanide is effective in the treatment of a number of viral infections.