Rifaximin 400mg tablets are a gut-selective rifamycin antibiotic used in gastrointestinal conditions where localized antibacterial action is desired, notably infectious traveler’s diarrhea due to noninvasive E. coli, hepatic encephalopathy prevention in chronic liver disease, and symptom relief in IBS with diarrhea, with widespread availability of 400mg products in India across multiple brands and listings. The 400mg strength is commonly utilized in practice and studied across GI indications, with evidence supporting use in IBS-D and infectious diarrhea while formal labeling varies by market compared with 200mg (traveler’s diarrhea) and 550mg (HE, IBS-D) strengths. Rifaximin remains minimally absorbed, acting locally in the intestine.