Nitazoxanide 500mg typically starts working within a few hours to a couple of days, depending on the infection being treated. For parasitic infections like Cryptosporidium or Giardia, symptoms may improve within 2-3 days of starting the medication. In viral gastroenteritis, relief can begin within 24-48 hours. It is essential to complete the full course of nitazoxanide 500mg as prescribed, even if symptoms improve earlier, to ensure the infection is fully cleared. If symptoms persist beyond the expected timeframe, consult a healthcare professional for further evaluation and possible alternative treatments. Always follow medical guidance when using Nitazoxanide 500mg.