Rifaximin (Oral)

Rifaximin is often prescribed to travellers to prevent or treat diarrhea that can be due to the Escherichia coli and irritable bowel syndrome, it also prevents hepatic encephalopathy in patients whose livers do not function normally.


Travellers are often prescribed rifaximin to treat diarrhea that is due to a bacteria known as Escherichia coli. It can also be an effective treatment for diarrhea that is one of the symptoms of irritable bowel syndrome and to lessen the chances of contracting hepatic encephalopathy by patients whose liver does not function properly. It should be noted that this antibiotic is not effective in treating colds, cases of flu or other ailments that are caused by a virus.

Due to the effectiveness of this medication, many patients experience relief from their symptoms after just a few doses. However, it is very important to continue taking the drug for the entire prescribed course of treatment to ensure that the infection is completely eradicated and that your condition is effectively treated. Do not take this medication for longer than prescribed, or in a higher dose.

Patients that suffer from liver disease or diarrhea that is not due to the bacteria Escherichia coli should not take rifaximin, their doctor will likely find an alternative medication for their treatment.

There are a number of side effects that can be a signal of a more serious problem and should not be ignored. If you experience any of these symptoms be sure to contact your prescribing physician immediately for further medical guidance. While some side effects warrant immediate care, there are others that will typically go away on their own. If you experience any of these symptoms and they linger for longer than a day or two or become worse, it is always best to contact your doctor for further guidance.

Conditions Treated

Diarrhea that is due to or related to:

  • Escherichia coli
  • Irritable Bowel Syndrome

The Prevention of

  • Hepatic Encephalopathy

Type of Medicine

  • Rifamycin (Antibiotic)

Side effects

There are a number of side effects that can be harmful and should be immediately reported to your doctor as further medical attention may be warranted:

More Likely:

  • Rapid breathing
  • Muscle spasm
  • Dizziness or lightheadedness
  • Shortness of breath
  • Black, tarry stools
  • Trouble sleeping

Less Likely:

  • Unusual tiredness or weakness
  • Bloody nose
  • Ulcers, sores, or white spots in the mouth
  • The sensation of spinning
  • Fainting
  • Sunken eyes
  • Increased heart rate
  • Continuing ringing or buzzing or other unexplained noise in the ears
  • Unusual bleeding or bruising
  • The feeling of constant movement of self or surroundings
  • Chest pain
  • Blood in the urine

Unknown Likelihood:

  • Scaly skin
  • Hives or welts, itching skin, or rash
  • Redness of the skin
  • Red, swollen skin
  • Loss of heat from the body
  • Cracks in the skin
  • Huge welts that are similar to hives

While the side effects above do require immediate medical attention, there are other symptoms that can occur that are less serious. The side effects below will likely dissipate on their own after a few days and do not warrant further treatment. If you experience any of these and they become worse or do not go away on their own after a few days, it is always best practice to consult with the prescribing physician for further guidance.

More Likely:

  • Swelling of the hands, ankles, feet, or lower legs
  • Excess air or gas in the stomach or intestines
  • Difficulty with moving
  • Frequent urge to defecate
  • Muscle pain or stiffness
  • Headache
  • Lower back or side pain
  • Stomach pain
  • Pain in the joints
  • Full feeling
  • Passing gas
  • Fever
  • Straining while passing stool
  • Feeling bloated

Less Likely:

  • Thirst
  • Blurred vision
  • Sweating
  • Confusion
  • Redness of the face, neck, arms, and occasionally, upper chest
  • Decreased urination
  • Painful or difficult urination
  • Dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • Loss of taste
  • Dry mouth
  • Lightheadedness
  • Feeling of warmth
  • Loss of appetite
  • Ear pain
  • Nausea
  • Lips that are dry
  • Pale skin
  • Difficulty having a bowel movement
  • Sore throat
  • Cough
  • Hearing loss
  • Swollen glands
  • Chills
  • Vomiting
  • Abnormal dreams
  • Wrinkled skin

While this list contains many of the symptoms that can occur when taking rifaximin, it is by no means comprehensive and you may experience side effects that are not listed here. If you are unsure if you are experiencing ill effects that require medical attention, it is always best to check with your doctor or pharmacist for further guidance.


Rifaximin is used in the treatment of three separate ailments and the prescribed dosage can differ depending on why you are taking the medication. Be sure to follow your doctor's instructions and remember to take the medication for the entire course of treatment even if you begin to feel better.

If you miss a dose, take it as soon as possible, unless it is close to the scheduled time of your next dose as you do not want to take double the prescribed amount. if you have missed a dose and are unsure how to proceed, or if you have any questions relating to dosage, be sure to consult with your prescribing physician or pharmacist for guidance.

Rifaximin is available in tablet form and should be taken in the following doses unless otherwise instructed by the prescribing physician:

To treat diarrhea that is associated with the presence of irritable bowel syndrome:
Children over the age of 12 and adults are typically prescribed 550 milligrams, three times per day for a course of treatment lasting 14 days.

Diarrhea that is related to the presence of Escherichia coli in travellers:
Adults, as well as children who are over the age of 12 years of age, are generally prescribed 200 milligrams three times per day, every day for three days.

Patients that are taking rifaximin to prevent hepatic encephalopathy:
Rifaximin is not typically an effective or common treatment for children with this condition, and the adult dosage is 550 milligrams taken two times per day for the length of time prescribed by your doctor.

Children under the age of 12 can be prescribed varying amounts of rifaximin and should follow the directions provided by their doctor or pediatrician.

Take this and all medications as instructed by your doctor, and confer with them for guidance if you have any questions relating to the amount of this medication that you should be taking.


There are two drug interactions that may prevent your doctor from prescribing rifaximin, and those are:

  • Live cholera vaccine
  • Eliglustat

If you are currently taking one of these drugs, your physician may change one or more of your medications, alter the dosage and frequency of one or both of the drugs, or prescribe an alternative.

In addition to these major drug interactions, there are several medical conditions that can make rifaximin a less than ideal option. Those are:

  • Severe liver disease
  • Diarrhea not due to the presence of Escherichia coli
  • Diarrhea due to antibiotics
  • Diarrhea and blood in the stool
  • ¬†Diarrhea with fever

If you suffer from any of the above conditions, be sure to inform your doctor prior to beginning any course of treatment that includes rifaximin.

As with any medication, it is important to discuss all current conditions and medications that you are taking prior to beginning your rifaximin course of treatment. Inform them of all medications that you are currently taking, whether they are prescription or non-prescription drugs. Also, let them know of any herbal remedies that you take as well as any vitamin or mineral supplements.


If your diarrhea does not end within one to two days after taking rifaximin, consult with your doctor for further medical guidance and direction. It is also important to let them know if you develop a fever or have blood in your stool while you are taking rifaximin.

Dehydration is a common ailment in patients who are suffering from diarrhea and it is important that you notify your doctor immediately if you experience any of the symptoms of dehydration, such as: feeling faint or lightheaded, dizziness, excessive thirst, dry mouth and an increased frequency of urination. Dehydration can lead to more serious health issues if it is not addressed immediately.

Currently, there is no information or warnings that have been issued regarding the use of rifaximin in older or elderly patients. If you are a woman who is pregnant, nursing, or may become pregnant in the near future, be sure to advise your doctor of such conditions prior to beginning your rifaximin course of treatment. Advise your doctor of any changes in your overall health or lifestyle that occur while you are taking rifaximin.


It is always best to store any medication in its original packaging and away from direct light, moisture, extreme heat or cold. Do not allow your rifaximin to freeze.

Keep this and all medications out of the reach of children.

Do not store excess or unused medication after you complete your course of treatment. If you have medication that you did not use or is expired, check with the prescribing physician or your pharmacist about the most appropriate way to dispose of the medication.


Rifaximin is an effective treatment for diarrhea in travellers that is due to the presence of Escherichia coli bacteria or is related to irritable bowel syndrome. It is also used successfully in the prevention of Hepatic Encephalopathy of patients whose liver does not function normally.

Patients who are taking rifaximin need to be aware of the chance of dehydration and notify their doctor if they experience any symptoms such as fainting or lightheadedness. If you experience any of these symptoms it is important to seek medical attention as dehydration can cause additional medical issues if not properly treated in a timely manner.

While some patients do report relief from their symptoms after just a few doses of rifaximin, it is important that the entire course of treatment be taken to ensure that the infection is cleared up completely. If you have any questions relating to the proper dosage or frequency at which you should take rifaximin for your symptoms, be sure to consult with your physician or pharmacist for guidance.

Because it is an antibiotic, rifaximin is not an effective treatment for cases of the flu or for the treatment of the common cold or any other ailment that is caused by a virus.

This medication is only available by prescription, and all directions given by your doctor must be followed for it to work effectively. Do not take a double dose of this medication in cases where you might skip a dose; consult with your doctor or pharmacist for guidance in such situations.

Always inform your doctor of any medical conditions for which you are currently being treated, and all of the medications that you are currently taking including both prescription and non-prescription strength as well as any herbal remedies or supplements.

This medication should not be taken by patients that have recently received the live cholera vaccine or are taking the drug named Eliglustat.


Last Reviewed:
January 30, 2018
Last Updated:
April 05, 2018