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Antibiotic

Rifaximin

Brand names: Targaxan, Xifaxan

Rifaximin is a gut-selective antibiotic used to reduce the recurrence of overt hepatic encephalopathy, usually alongside lactulose, and is also used for travellers' diarrhoea.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

Condition Recommended Oral Dosage TD ( 2.1 ) 200 mg 3 times a day for 3 days HE ( 2.2 ) 550 mg 2 times a day IBS-D ( 2.3 ) 550 mg 3 times a day for 14 days. Patients who experience recurrence can be retreated up to 2 times with the same regimen. XIFAXAN can be taken with or without food. ( 2.4 ) 2.1 Dosage for Travelers’ Diarrhea The recommended dosage of XIFAXAN is 200 mg taken orally three times a day for 3 days. 2.2 Dosage for Hepatic Encephalopathy The recommended dosage of XIFAXAN is 550 mg taken orally two times a day. 2.3 Dosage for Irritable Bowel Syndrome with Diarrhea The recommended dosage of XIFAXAN is 550 mg taken orally three times a day for 14 days. Patients who experience a …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-08-27. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It is a minimally absorbed, broad-spectrum antibacterial that inhibits bacterial RNA synthesis, acting largely within the gut lumen to reduce ammonia-producing enteric bacteria.

Prescribing in practice

  • For hepatic encephalopathy it is used to maintain remission and is normally added to, rather than replacing, lactulose.
  • Because systemic absorption is minimal, systemic adverse effects and drug interactions are few and it is generally well tolerated.
  • Clostridioides difficile infection has been reported rarely, so consider this if severe or persistent diarrhoea develops.

Monitoring

No specific routine monitoring is required for the encephalopathy indication; assess clinical response and tolerability and continue lactulose as indicated.

Counselling the patient

  • For hepatic encephalopathy, keep taking your lactulose as well unless told otherwise.
  • Report severe, persistent or bloody diarrhoea rather than treating it yourself.

Evidence & guidelines

Recommended to reduce recurrence of hepatic encephalopathy (NICE TA337).

Reference: SONIC Trial Lancet 2010; NICE NG215 Cirrhosis; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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