Rifaximin is a unique, structural non-systemic antibiotic belonging to the rifamycin family. Due to its complex multi-ring configuration and low water solubility, it possesses negligible systemic absorption (less than 1%), remaining tightly concentrated within the gastrointestinal lumen. It acts by binding to the beta-subunit of bacterial DNA-dependent RNA polymerase, inhibiting bacterial transcription. This action sanitizes the gut lumen, lowers ammonia-producing bacterial strains to manage hepatic encephalopathy, and balances microflora profiles to reduce diarrheal IBS symptoms without disturbing systemic tissues.