Rifabiz-400 (Rifaximin 400 mg) is a broad-spectrum, non-systemic antibiotic primarily used for treating bacterial infections in the gastrointestinal tract. It is commonly prescribed for traveler’s diarrhea, irritable bowel syndrome with diarrhea (IBS-D), and hepatic encephalopathy. Rifaximin works by inhibiting bacterial RNA synthesis, thereby reducing harmful bacteria in the gut while maintaining the natural gut flora.