A gut-acting antibiotic
Rifaximin
An antibiotic that stays mostly in the gut, used to prevent recurrence of hepatic encephalopathy and for some other bowel conditions.
What is Rifaximin?
Rifaximin is an antibiotic that works almost entirely inside the gut, because very little of it is absorbed into the rest of the body. Its main UK use is to prevent the return of hepatic encephalopathy, a confusion-and-drowsiness problem that can happen with serious liver disease, often alongside a medicine called lactulose. It is also used for travellers' diarrhoea and, in some settings, for symptoms of irritable bowel syndrome with diarrhoea. Because it stays in the gut, it is generally very well tolerated, with few effects elsewhere in the body. It is taken as a tablet for the length of time your prescriber advises.
Education and reference only. This is a plain-language guide to Rifaximin — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Rifaximin is an antibiotic that is barely absorbed from the gut, so it acts on bacteria in the bowel while having little effect on the rest of the body. In the UK its main role is preventing repeat episodes of hepatic encephalopathy in people with liver disease, where toxins from gut bacteria affect the brain. It is also used to treat travellers' diarrhoea and, in some settings, irritable bowel syndrome with diarrhoea. It is taken by mouth as a tablet.
How it works
In hepatic encephalopathy, bacteria in the bowel produce substances such as ammonia that a damaged liver cannot clear, and these affect the brain, causing confusion and drowsiness. Rifaximin reduces these bacteria within the gut, lowering the toxins that reach the brain and helping to prevent further episodes. For travellers' diarrhoea and some bowel symptoms, it works by acting on the bacteria in the gut that contribute to the problem, all while staying mostly where it is needed.
Company & origin
Originated / developed by: Norgine.
A poorly absorbed antibiotic used in the UK to prevent recurrence of hepatic encephalopathy and, in some settings, for travellers' diarrhoea and certain bowel symptoms.
What it treats
Conditions Rifaximin is used for
Practical use
How to take Rifaximin
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take the tablets regularly as prescribed; if it is for hepatic encephalopathy, this is usually long term alongside lactulose.
- For travellers' diarrhoea, take the short course as directed and complete it.
- It can be taken with or without food, with a drink of water.
- Do not use it for diarrhoea with a high fever or blood in the stools without medical advice, as this needs different assessment.
- Keep taking it for prevention even when you feel well, as stopping can allow episodes to return.
- Tell your prescriber if diarrhoea becomes severe or lasts, in case of another gut infection.
Weighing it up
Advantages & disadvantages of Rifaximin
Advantages
- Stays almost entirely in the gut, so it is generally very well tolerated with few effects elsewhere.
- Reduces repeat episodes of hepatic encephalopathy and related hospital admissions, especially with lactulose.
- Offers a short, effective option for travellers' diarrhoea and some bowel symptoms.
Disadvantages
- As an antibiotic, it can still occasionally cause bloating, wind or diarrhoea.
- It is not suitable for diarrhoea with fever or blood in the stools, which need different treatment.
- Long-term preventive use means taking it regularly even when feeling well.
Practical use
Good to know
The standout feature of rifaximin is that it stays almost entirely in the gut, so it is generally very well tolerated and causes few of the wider effects seen with antibiotics that spread through the body. For hepatic encephalopathy it is usually taken alongside lactulose, and together they reduce the chance of further confusing episodes and hospital admissions; it is a preventive treatment, so it is taken regularly rather than only when symptoms appear. For travellers' diarrhoea it is a short course, and it is not suitable if there is fever or blood in the stools, which need different assessment. As with any antibiotic, it can occasionally upset the gut or, rarely, lead to other bowel infections, so report severe or persistent diarrhoea. It is generally avoided in pregnancy unless your doctor advises otherwise.
Who should not take it / use with caution
- People with a known allergy to rifaximin or related antibiotics should not take it.
- It is not suitable for diarrhoea with high fever or blood in the stools without proper assessment.
- It is generally avoided in pregnancy unless a doctor specifically advises it.
Monitoring
- Reviewing whether episodes of hepatic encephalopathy are being prevented.
- Checking that diarrhoea has settled after a course, and reassessing if it has not.
- Watching for severe or persistent diarrhoea that could signal another gut infection.
Side effects
- Bloating, wind, stomach discomfort or changes in bowel habit in some people.
- Headache or dizziness occasionally.
- Rarely, a different bowel infection causing severe or persistent diarrhoea, which should be reported.
Key interactions
- Because little is absorbed, it has fewer body-wide interactions than many antibiotics.
- It may interact with certain medicines such as some used to prevent transplant rejection, so tell your prescriber what you take.
- Always mention other medicines, as occasional interactions through the gut or liver can occur.
Available as: Tablets taken by mouth.
Answers
Rifaximin: frequently asked questions
Why doesn't rifaximin cause many side effects elsewhere in the body?
Very little of it is absorbed from the gut, so it acts on bowel bacteria while having little effect on the rest of the body, which is why it is generally well tolerated.
What is it used for in liver disease?
It is used to prevent the return of hepatic encephalopathy, a confusion-and-drowsiness problem in serious liver disease, usually alongside a medicine called lactulose.
Can I use it for any kind of diarrhoea?
No, it is not suitable for diarrhoea with a high fever or blood in the stools, which need different assessment; use it only as advised.
Do I keep taking it even when I feel well?
For prevention of hepatic encephalopathy, yes, it is taken regularly even when you feel well, as stopping can let episodes return.
Is it safe in pregnancy?
It is generally avoided in pregnancy unless your doctor specifically advises it, so let your team know if you are or might be pregnant.
Authoritative sources
- BNF
- NICE CKS
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