Nitazoxanide is an antiparasitic and broad-spectrum antiprotozoal medication primarily used to treat gastrointestinal infections caused by parasites such as Giardia lamblia and Cryptosporidium parvum. It works by interfering with the energy metabolism of the parasites, leading to their death. Nitazoxanide is also being investigated for its potential antiviral activity against certain viruses, including hepatitis B and C, influenza.