Rifaximin (available in 200mg, 400mg, and 550mg doses) is a broad-spectrum, non-absorbable antibiotic primarily used to treat gastrointestinal infections. It works by inhibiting bacterial RNA synthesis through binding to the bacterial RNA polymerase, which prevents the bacteria from replicating. Rifaximin is commonly prescribed for conditions such as traveler’s diarrhea, irritable bowel syndrome with diarrhea (IBS-D), and hepatic encephalopathy (a liver-related condition that affects brain function). It is also used to treat certain types of gut infections, particularly those caused by Gram-negative and Gram-positive bacteria.

Because Rifaximin is poorly absorbed in the gut, it mainly acts locally within the gastrointestinal tract, minimizing systemic side effects. The 200mg dose is typically prescribed for traveler’s diarrhea or small intestine bacterial overgrowth (SIBO), while the 400mg or 550mg doses are more often used for IBS-D and hepatic encephalopathy. Rifaximin is generally well-tolerated, but like any antibiotic, it should be used according to the prescribing doctor’s instructions to avoid resistance development.