Travellers diarrhoea caused by non-invasive E. coli, prevention of repeat episodes of hepatic encephalopathy in liver disease, and, in some countries, irritable bowel syndrome with diarrhoea and small intestinal bacterial overgrowth.

Rifaximin blocks bacterial RNA polymerase, the enzyme a bacterium uses to read its genes, which stops it making proteins and kills it. Because almost none of the drug crosses the gut wall into the blood, its whole effect is concentrated on the bacteria in the bowel.

Wind, bloating, stomach pain, nausea, headache and dizziness. It is generally well tolerated because so little is absorbed.

Rifaximin is not the right treatment for diarrhoea with fever or blood in the stool, which points to an invasive infection that needs a different antibiotic. Stop and seek advice if the diarrhoea worsens or does not improve within 24 to 48 hours. Tell your doctor about severe liver disease. It is a prescription medicine in Pakistan.