saudigastro.com/patients/rifaximin
This article is educational and does not replace your doctor's advice. Seek urgent care for any red-flag symptoms.
Drug class
A poorly absorbed (gut-acting) antibiotic of the rifamycin family
Examples
Rifaximin is available under several brand names depending on the country. Ask your pharmacist for the product available to you.
How it works
Most antibiotics are absorbed into the blood and act throughout the body. Rifaximin is absorbed only in very small amounts, so it stays mostly in the gut, where it changes the balance of the bacteria that live there. In liver disease, some gut bacteria produce substances, such as ammonia, that can reach the brain when the liver cannot clear them and cause confusion (hepatic encephalopathy). By reducing these bacteria, rifaximin lowers the load of these substances. In other conditions it reduces the gut bacteria thought to cause bloating, gas and diarrhea.
What it treats
- Preventing episodes of hepatic encephalopathy from coming back in people with cirrhosis, usually together with lactulose
- Treating episodes of hepatic encephalopathy in some cases, as decided by the specialist
- Irritable bowel syndrome with diarrhea, in selected patients
- Traveller's diarrhea caused by certain non-invasive bacteria
- Small intestinal bacterial overgrowth (SIBO) in some cases, a use that depends on local approval and your specialist's judgement
How to take it
Take rifaximin exactly as your doctor prescribes: the amount, the number of times a day and the length of treatment are decided for your condition and are not the same for everyone. It is taken by mouth and can be taken with or without food. When used to prevent hepatic encephalopathy it is usually a long-term medicine and should not be stopped on your own, even if you feel well. If you miss a dose, take the next dose at the usual time and do not double up; ask your pharmacist if unsure.
Common side effects
- Nausea
- Bloating or gas
- Headache or dizziness
- Mild belly pain or diarrhea
- Swelling of the hands or feet or tiredness in some people with liver disease
Serious side effects — call your doctor
Swelling of the face, lips or throat, difficulty breathing, hives or a widespread rash
May be a serious allergic reaction. Stop the medicine and seek emergency care immediately.
Severe, watery or bloody diarrhea that does not stop, with belly cramps or fever
Antibiotics can allow a bowel infection called Clostridioides difficile to grow. Contact your doctor urgently or go to the emergency department.
Worsening confusion, extreme sleepiness, or fainting
May be hepatic encephalopathy getting worse or another illness. This needs urgent medical assessment.
Fever, chills or new belly pain and swelling
May be an infection in someone with liver disease. Seek medical care the same day.
Yellow skin or eyes, dark urine or severe tiredness
May show your liver disease is worsening. Contact your doctor promptly.
Interactions
Tell your doctor and pharmacist about all medicines you take. Some medicines, such as cyclosporine and certain medicines that affect drug transporters in the gut, can raise rifaximin levels in the blood, and rifaximin may affect some medicines such as warfarin (blood thinner), so blood tests may be needed. Rifaximin may reduce how well some oral birth control pills work in some people, so ask about extra contraception. Do not take it if you are allergic to rifaximin or other rifamycin antibiotics.
Monitoring
Your doctor will follow your symptoms, mental state, liver and kidney blood tests and, if you take blood thinners such as warfarin, clotting tests. Tell your doctor if you develop new diarrhea while on treatment.
When and how to stop
Do not stop rifaximin on your own, particularly if you take it to prevent hepatic encephalopathy, since stopping may allow confusion to come back. Stop and seek emergency care only for signs of a severe allergic reaction, and call your doctor if you have severe diarrhea or other serious side effects. Your doctor decides if and when treatment can stop or be changed.
Pregnancy & breastfeeding
There is limited information about the use of rifaximin in pregnancy and breastfeeding. Tell your doctor if you are pregnant, planning pregnancy or breastfeeding so that benefits and risks can be weighed. Do not start or stop it without medical advice.
Questions to ask your doctor
Save this list or print it before your appointment — doctors appreciate prepared patients.
- Why am I taking rifaximin, and for how long?
- Do I need to take lactulose as well?
- Is it safe with my other medicines, including blood thinners?
- What should I do if I get diarrhea or confusion?
- How will you check that it is working?
Was this guide helpful?
Status: Approved for publication by SGA; individual clinician review is ongoing · Published 24/04/2026
For general education only; it does not replace your doctor’s advice. Individual clinician review of this guide is ongoing. SGA clinician? Review this guide