Nizonide 500mg is an antiparasitic medication containing nitazoxanide as its active ingredient. It is commonly used to treat infections caused by protozoa, such as Giardia and Cryptosporidium, which lead to conditions like diarrhea. This medication works by inhibiting the growth of the parasites. It should be taken as directed by a healthcare professional, and common side effects may include nausea, headache, or abdominal pain.