Rifaximin is a type of antibiotic medication taken orally in the form of a pill. Rifaximin is used to kill infections of the gastrointestinal system caused by the bacteria E. coli. The drug is not effective against infections caused by viruses or other types of bacteria outside the digestive tract. Rifaximin is a unique antibiotic drug because it is absorbed by the mucosal lining of the stomach and works directly through the intestines. It does not need to be absorbed into the bloodstream to take effect. Rifaximin is most commonly used to combat traveler's diarrhea, caused by drinking foreign water or consuming foreign food. For this reason, Rifaximin is often given to people traveling abroad. It is also approved for the treatment of chronic hepatic encephalopathy in people with liver disease. Rifaximin requires a prescription and cannot be purchased over-the-counter.