Nitazoxanide 500 mg is an antiparasitic and antiviral medication used to treat infections caused by protozoa, helminths, and some viruses. It is commonly prescribed for giardiasis, an intestinal infection caused by Giardia lamblia, and cryptosporidiosis, caused by Cryptosporidium parvum. Nitazoxanide works by interfering with the energy metabolism of parasites, effectively eliminating them. It is also studied for its potential use against viral infections like rotavirus and norovirus. Typically taken orally with food, the dosage and duration depend on the infection being treated. Side effects may include nausea, diarrhea, and abdominal pain. Always follow medical advice for proper use.