Rifaximin is an antibiotic used to treat bacterial infections of the intestine (traveller’s  diarrhea). Rifaximin is also used to lower the risk of worsened brain function in adults with liver failure. Brain function can be affected when the liver stops working and cannot remove toxic substances from the body.

Rifaximin is a broad spectrum antibacterial drug that fights bacterial infection only in the intestines. Rifaximin stops the growth of bacteria that produce toxins and that may worsen liver disease.

What is rifaximin?

Rifaximin is an antibiotic that fights bacterial infection only in the intestines. Rifaximin works differently from other antibiotics because it passes through your stomach and into your intestines without being absorbed into your blood stream. Because rifaximin treats only the intestinal tract, it will not treat infections of other parts of the body. Rifaximin is used to treat travelers’ diarrhea caused by E. coli in adults and children who are at least 12 years old. Most people get this infection by eating food or drinking fluids that have been contaminated with the E. coli bacteria. Rifaximin is also used to treat irritable bowel syndrome in adults whose main symptom is diarrhea. Rifaximin is also used to lower the risk of worsened brain function in adults with liver failure. Brain function can be affected when the liver stops working and cannot remove toxic substances from the body. Rifaximin may also be used for purposes not listed in this medication guide.

What is the most important information I should know about rifaximin?

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

What should I discuss with my healthcare provider before taking rifaximin?

You should not take this medicine if you are allergic to rifaximin, rifabutin, rifampin, or rifapentine. To make sure rifaximin is safe for you, tell your doctor if you have: liver disease; diarrhea with a fever; or watery or bloody diarrhea. It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant. It is not known whether rifaximin passes into breast milk or if it could harm a nursing baby. You should not breast-feed while using this medicine. Rifaximin should not be given to a child younger than 12 years old.

How should I take rifaximin?

Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended. You may take rifaximin with or without food. Use this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Rifaximin will not treat a viral infection such as the flu or a common cold. Call your doctor if your symptoms do not improve after 24 hours, or if they get worse while using rifaximin. Rifaximin does not treat all bacterial forms of traveler’s diarrhea. Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking rifaximin?

Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, call your doctor. Do not use anti-diarrhea medicine unless your doctor tells you to.

Rifaximin side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat. Stop using rifaximin and call your doctor at once if you have: severe stomach pain, diarrhea that is watery or bloody; fever; or rapid weight gain, especially in your face and midsection. Common side effects may include: swelling in your hands, feet, or midsection; headache, dizziness; tired feeling; or abnormal liver function tests.

Rifaximin dosing information

Usual Adult Dose for Traveler’s Diarrhea: 200 mg orally 3 times a day for 3 days -Should not use in patients with diarrhea complicated by fever and/or blood in the stool or diarrhea caused by pathogens other than Escherichia coli Use: For the treatment of travelers’ diarrhea due to noninvasive strains of E coli

Usual Adult Dose for Hepatic Encephalopathy:

550 mg orally twice a day Comments: -In trials, lactulose was used concomitantly in 91% of patients; differences in treatment effect of patients not using concomitant lactulose could not be assessed. Use: For reduction in risk of overt hepatic encephalopathy recurrence

Usual Adult Dose for Irritable Bowel Syndrome:

550 mg orally 3 times a day for 14 days Comments: -If symptoms recur, patients can be retreated up to 2 times with the same dose regimen. Use: For the treatment of irritable bowel syndrome with diarrhea

Usual Pediatric Dose for Traveler’s Diarrhea:

12 years or older: 200 mg orally 3 times a day for 3 days Comments: -Should not use in patients with diarrhea complicated by fever and/or blood in the stool or diarrhea caused by pathogens other than E coli Use: For the treatment of travelers’ diarrhea due to noninvasive strains of E coli