A new article published in the Expert Opinion on Drug Metabolism and Toxicology reported that rifaximin is a broad-spectrum antibiotic against both Gram-negative and -positive bacteria, and exhibits limited bioabsorbability. The drug is active in the small intestine due to its high bile solubility. On the other hand, in aqueous environment of the colon it shows limited efficacy. These unique properties of this drug limit its systemic effects and can correct gut microflora imbalances. Hence, rifaximin is an effective therapeutic agent in several gastrointestinal diseases which manifest due to an imbalance in the gut microflora, including diarrhea predominant irritable bowel syndrome (IBS-D). The authors stated that owing to its safety profile and negligible absorption, rifaximin is a suitable treatment for IBS-D, in both adults and children. The drug modulates gut microbiota composition without side effects, and therefore, has emerged as a therapeutic agent of choice in highly prevalent gastrointestinal diseases.