rifaximin at a glance
Medicine class
Gut-acting rifamycin antibiotic
Licensed role
Reducing recurrence of overt hepatic encephalopathy in adults
Food
May be taken with or without food
Absorption
Very little normally reaches the bloodstream
Urine colour
A harmless reddish discolouration can occur
What is rifaximin used for?
The selected UK product is licensed for:
Reducing recurrence of overt hepatic encephalopathy in adults with liver disease. It may be used alone but is commonly prescribed alongside lactulose.
How does rifaximin work?
Rifaximin binds bacterial RNA polymerase and prevents susceptible gut bacteria from making RNA. Its local action suppresses ammonia-producing bacteria and may reduce ammonia and other gut-derived compounds involved in hepatic encephalopathy.
rifaximin preparations and strengths
Tablet
Route: Oral
Strengths: 200 mg, 550 mg
How to take rifaximin
Follow the prescriber's directions and the dispensing label.
Take the tablet by mouth with a glass of water.
It may be taken with or without food.
Continue until the prescriber advises otherwise; stopping may allow symptoms to return.
Reddish urine can occur and is usually harmless.
rifaximin side effects
Common or expected effects
- Feeling or being sick, abdominal discomfort or bloating, or diarrhoea
- Dizziness or headache
- Rash or itching
- Muscle cramps or joint pain
- Swelling of the ankles, feet or fingers
- Low mood or shortness of breath
Get urgent medical advice
- Severe blistering, peeling or target-like skin rash, particularly with fever or mouth, eye or genital ulcers
- Facial, tongue or throat swelling, hives, swallowing difficulty or breathing difficulty
- Severe or persistent diarrhoea, including after treatment has ended
- Unexpected bleeding or bruising
- Marked worsening of confusion, drowsiness or alertness
rifaximin in pregnancy
Human pregnancy information is limited, and the UK product information advises against rifaximin during pregnancy as a precaution. Anyone pregnant, planning pregnancy or becoming pregnant during treatment should contact their prescriber for specialist review rather than stopping independently.
rifaximin while breastfeeding
It is unknown whether rifaximin or its metabolites enter breast milk, so risk to a breastfed child cannot be excluded. The prescriber should weigh the importance of treatment against the benefits of breastfeeding and agree an individual plan.
rifaximin interactions
Tell the prescriber or pharmacist about all medicines, including these important examples:
Warfarin and other oral anticoagulants
Rifaximin has been associated with increases or decreases in INR; closer monitoring may be required when it is started or stopped.
Ciclosporin
Ciclosporin can markedly increase systemic exposure to rifaximin, so concurrent use requires caution.
Other rifamycin antibiotics
Concurrent use is not recommended because evidence is lacking and substantial disruption of gut flora is possible.
Common questions about rifaximin
Answers are fully visible for fast scanning and source review.
What is rifaximin used for in liver disease?
It is used to reduce the chance of overt hepatic encephalopathy returning in adults with liver disease.
Does rifaximin treat sudden severe hepatic encephalopathy?
The selected UK product is licensed to reduce recurrence, not as an acute rescue treatment. New confusion or reduced alertness requires urgent clinical assessment.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.