Nizonide 500mg Tablet contains nitazoxanide, an antiparasitic medication used to treat infections caused by protozoa, helminths, and certain viruses. It is commonly prescribed for diarrhea due to Giardia or Cryptosporidium, and other gastrointestinal infections. Additionally, it helps manage infections in immunocompromised patients and sometimes treats parasitic or bacterial skin infections. Always follow medical advice.