This page contains brief details about the drug , it's indication, dosage & administaration, mechanism of action, related brands with strength, warnings and common side effects.

Background and Date of Approval

Rifaximin is an antibiotic and received its initial approval from the U.S. Food and Drug Administration (FDA) on May 27, 2004.

Mechanism of Action of undefined

Rifaximin acts by binding to the bacterial DNA-dependent RNA polymerase blocking one of the steps in the transcription process. This results in the inhibition of bacterial protein synthesis and consequently inhibits the growth of bacteria.

Uses of undefined

It is used to treat traveler’s diarrhea caused by noninvasive strains of Escherichia coli in adults. It is also used to prevent the recurrence of episodes of overt hepatic encephalopathy (symptomatic loss of brain function) in adults with liver disease. This medicine can be used alone or in combination with medicines containing lactulose.  

undefined Drug administaration and Dosage available

Rifaximin is available as a tablet in doses of 200mg, 400mg, and 550mg. Always use this medicine as exactly prescribed by your doctor. Depending on the condition being treated, your physician decides the dose, dosage, and duration of the treatment. Take the tablet at the same time every day, with or without food. Swallow the tablets with a glass of water. Do not break, crush, or chew the tablets.

Warnings, Precautions and Side Effects of undefined


Do not take Rifaximin if you are allergic to Rifaximin or any of the other ingredients of this medicine. Do not take this medicine if you are allergic to similar types of antibiotics, such as rifamycin, rifampicin, or rifabutin. Do not take this medicine if your physician informs you that you have a blockage in your intestine. Do not take this medicine if you have a fever, blood in stools, or have passed over eight or more unformed stools in the last 24 hours.


This medicine is not recommended for children and adolescents aged less than 18 years of age. Inform your physician if you have liver problems before starting the treatment.  Inform your physician if you are pregnant or breastfeeding. If you take more than the recommended number of tablets unknowingly, seek medical advice immediately. Inform your healthcare provider about all the medicines you take, including prescription, over-the-counter, vaccines, nutritional or vitamin supplements, and herbal products. Certain medications like warfarin, and oral contraceptives may interact with Rifaximin and reduce their effectiveness by causing undesirable side effects. 

Side Effects

The common side effects of rifaximin are swelling of the legs and feet, abdominal pain, nausea, abdominal swelling, dizziness, headache, and tiredness. Other serious side effects are allergic reactions and anemia. 

Word Of Advice

While taking rifaximin your urine may occur as a reddish colour. Treatment with this medicine can cause severe diarrhea. Inform your physician if you have diarrhea for several weeks. If you forgot to take the tablet, take it as soon as you remember. However, skip the missed dose if it is nearly time for the next dose.  Inform your physician if you are taking oral contraceptives (medicines to prevent pregnancy). Your doctor may suggest you to take certain tests to monitor the effectiveness and side effects of the therapy.

Frequently Asked Question


The drug information on this page is not a substitute for medical advice. It is meant for educational purposes only. For further details, consult your doctor about your medical condition to know if you can receive this treatment.


  1. Norgine Pharmaceuticals Limited., Electronic Medicines Compendium (EMC), [Revised on October 2020] [Accessed on June 2023 ],
  2. Norgine Pharmaceuticals Limited., Electronic Medicines Compendium (EMC), [Revised on October 2020] [Accessed on June 2023 ],
  3. Camille E. Beauduy, Lisa G. Winston, Miscellaneous Antimicrobial Agents; Disinfectants, Antiseptics & Sterilants, Lange’s Basic & Clinical Pharmacology, 14th Edition, 2018, 895-903.
  4. I.D. Penman, C.W. Lees, Alimentary tract and pancreatic disease, Davidson’s Principles and Practice of Medicine, 22nd Edition, 2014, 837-920.
  5. Q.M. Anstee, D.E.J. Jones, Liver and biliary tract disease, Davidson’s Principles and Practice of Medicine, 22nd Edition, 2014, 921-988.