Rifaximin

Rifaximin is an oral antibiotic that is active in the gastrointestinal tract against both gram-positive and gram-negative bacteria, as well as, both aerobic and anaerobic bacteria. It is used to treat several other gastrointestinal conditions including traveler's diarrhea, irritable bowel syndrome, hepatic encephalopathy, and C. difficile infection. Among ME/CFS patients, it is commonly used as a treatment for Small Intestine Bacterial Overgrowth (SIBO).

Evidence
A meta-analysis published in 2017 concluded "Rifaximin treatment seems to be effective and safe for the treatment of SIBO. However, the quality of the available studies is generally poor. Well‐designed RCTs are needed to substantiate these findings and to establish the optimal regimen."

United States
Rifxamin is marketed with the brand name Xifaxan. As of May 2019, a 42-count bottle of 550mg Xifaxan pills is priced at approximately $1620 according to GoodRx. No generic is authorized in the United States at this time.

Due to the cost, insurance coverage for Rifaximin is limited. Many insurance plans require prior authorization paperwork. Patients who can get coverage are often subject to strict quantity / refill limits.

The combination of cost, lack of an approved generic, and insurance considerations cause many patients to look to foreign pharmacies.

Learn more

 * Xifaxan - Official website
 * Wikipedia