Rifaximin, is a non-absorbable, broad spectrum antibiotic mainly used to treat travelers diarrhea. It is based on the rifamycin antibiotics family. Since its approval in Italy in 1987, it has been licensed in over more than 30 countries for the treatment of a variety of gastrointestinal diseases like irritable bowel syndrome, and hepatic encephalopathy. It acts by inhibiting RNA synthesis in susceptible bacteria by binding to the RNA polymerase enzyme. This binding blocks translocation, which stops transcription. It is marketed under the brand name Xifaxan by Salix Pharmaceuticals. Medical uses
Travelers’ Diarrhea (TD)
Rifaximin is used to treat travelers diarrhea caused by certain bacteria (E. coli) in adults and children at least 12 years of age. It treats travelers diarrhea by stopping the growth of the bacteria that cause diarrhea. Rifaximin will not work to treat travelers diarrhea that is bloody or occurs with fever. Irritable Bowel Syndrome (IBS)
Rifaximin is used for the treatment of irritable bowel syndrome. It possesses anti-inflammatory and antibacterial properties, and is a nonabsorbable antibiotic that acts locally in the gut. These properties make it efficacious in relieving chronic functional symptoms of non-constipation type irritable bowel syndrome (IBS). It appears to retain its therapeutic properties for this indication, even after repeated courses. It is particularly indicated where small intestine bacterial overgrowth is suspected of involvement in a persons IBS. Symptom relief or improvement can be obtained for global IBS symptoms, including: abdominal pain, flatulence, bloating, and stool consistency. A drawback is that repeated courses may be necessary for relapse of symptoms.
It has also shown efficacy with rosacea, ocular rosacea which also presents as dry eyes for patients with co-occurrence with small intestinal bacterial overgrowth (SIBO). Special caution
Patients should avoid Rifaximin usage if they are allergic to Rifabutin, Rifampin and Rifapentine. It may cause attenuated vaccines (such as typhoid vaccine) to not work well. Health care professionals should be informed about its usage before having any immunizations. Pregnant or breastfeeding women should avoid taking it as it is a pregnancy category C drug and can harm the foetus. Cautious use is required in individuals with cirrhosis of the liver who have a Child-Pugh score of class C severity. Side effects
Rifaximin has an excellent safety profile due to its lack of systemic absorption. Clinical trials did not show any serious adverse events while using the drug. There were no deaths while using it in the clinical trials.The most common side effects includes nausea, stomach pain, dizziness, fatigue, headaches, muscle tightening and joint pain. It may also cause reddish discoloration of urine.The most serious side effects of Rifaximin are:

Clostridium difficile-associated diarrhea (CDAD)
Drug-resistant bacterial superinfection
Severe allergic reactions including hives, rashes and itching

Interactions
As Rifaximin is not significantly absorbed from the gut, the great majority of these drug interactions are negligible in people with healthy liver function, so healthcare providers usually do not worry about drug interactions unless liver impairment is present. It may decrease the effectiveness of warfarin, a commonly prescribed anticoagulant, in people with liver problems.