Rifaximin, sold under the brand name Xifaxan among others, is a non-absorbable, broad-spectrum antibiotic mainly used to treat travelers' diarrhea.

Since its approval in Italy in 1987, it has been licensed in more than 30 countries for the treatment of a variety of gastrointestinal diseases like irritable bowel syndrome and hepatic encephalopathy.

These properties make it efficacious in relieving chronic functional symptoms of non-constipation type irritable bowel syndrome.

[15] Rifaximin is used to prevent episodes of hepatic encephalopathy (changes in thinking, behavior, and personality caused by a build-up of toxins in the brain in adults who have liver disease).

It treats hepatic encephalopathy by stopping the growth of bacteria that produce toxins and that may worsen the liver disease.

People are more compliant and satisfied to take this medication than any other due to minimal side effects, prolonged remission, and overall cost.

[17] The drawbacks are increased cost, and lack of robust clinical trials for hepatic encephalopathy without combination lactulose therapy.

[25] Caution is required in people with cirrhosis who have a Child–Pugh score of C.[11] Rifaximin has an excellent safety profile due to its lack of systemic absorption.

[28] Rifaximin is a semisynthetic broad spectrum antibacterial drug, derived through chemical modification of the natural antibiotic rifamycin.

[33] In the United States, Salix Pharmaceuticals holds a US Patent for rifaximin and markets it under the brand name Xifaxan.

If rifaximin receives full FDA approval for hepatic encephalopathy it is likely that Salix will maintain marketing exclusivity and be protected from generic formulations until 24 March 2017.

[37] In August 2013, Health Canada issued a Notice of Compliance to Salix Pharmaceuticals for the drug product Zaxine.