Nitazoxanide 500 mg typically starts working within a few hours to a day after administration. Its onset of action can vary based on factors such as the individual's metabolism, the severity of the infection, and the specific condition being treated. Nizonide 500 is an antiparasitic and antiviral medication that works by interfering with the metabolism of parasites and viruses, inhibiting their growth and replication. It is commonly used to treat a variety of gastrointestinal infections and is generally well-tolerated. However, it's essential to follow medical guidelines and complete the prescribed course for optimal effectiveness in treating the targeted infection.