Trade Name(s)

  • Xifaxan
  • Zaxine Canadian Trade name

Ther. Class.


Pharm. Class.



  • Travelers' diarrhea due to noninvasive strains of Escherichia coli.
  • Reduction in risk of overt hepatic encephalopathy recurrence.
  • Treatment of irritable bowel syndrome with diarrhea


Inhibits bacterial RNA synthesis by binding to bacterial DNA-dependent RNA polymerase.

Therapeutic Effect(s):

  • Decreased severity of travelers' diarrhea.
  • Decreased episodes of overt hepatic encephalopathy.
  • Decreased signs/symptoms of irritable bowel syndrome with diarrhea.


Escherichia coli (enterotoxigenic and enteroaggregative strains).


Absorption: Poorly absorbed (<0.4%); action is primarily in GI tract.

Distribution: 80–90% concentrated in gut.

Metabolism and Excretion: Almost exclusively excreted unchanged in feces.

Half-life: 6 hr.




Contraindicated in:

  • Hypersensitivity to rifaximin or other rifamycins;
  • Diarrhea with fever or bloody stools;
  • Diarrhea caused by other infectious agents;
  • Lactation:  Lactation.

Use Cautiously in:

  • OB:  Use during pregnancy only if potential maternal benefit justifies potential fetal risk;
  • Pedi:  Safety not established in children <18 yr (hepatic encephalopathy or irritable bowel syndrome with diarrhea) or <12 yr (travelers' diarrhea).

Adverse Reactions/Side Effects

CV: peripheral edema


Neuro: dizziness

* CAPITALS indicate life-threatening.
Underline indicate most frequent.



  •  P-glycoprotein inhibitors, including  cyclosporine, may ↑ levels and risk of toxicity.
  • May cause fluctuations in INR when used with  warfarin ; closely monitor INR.


Travelers' Diarrhea

PO (Adults and Children  ≥12 yr): 200 mg 3 times daily for 3 days.

Hepatic Encephalopathy

PO (Adults): 550 mg twice daily.

Irritable Bowel Syndrome With Diarrhea

PO (Adults): 550 mg 3 times daily for 14 days; if recurrence of symptoms, may treat up to an additional 2 times.


Tablets: 200 mg, 550 mg


  • Traveler's Diarrhea: Assess frequency and consistency of stools and bowel sounds prior to and during therapy.
  • Assess fluid and electrolyte balance and skin turgor for dehydration.
  • Hepatic Encephalopathy: Assess mental status periodically during therapy.
  • Irritable Bowel Syndrome With Diarrhea: Assess frequency and consistency of stools and other irritable bowel syndrome symptoms (bloating, cramping) daily.
  • Monitor bowel function. Diarrhea, abdominal cramping, fever, and bloody stools should be reported to health care professional promptly as a sign of CDAD. May begin up to several wk following cessation of therapy.

Lab Test Considerations:

May cause lymphocytosis, monocytosis, and neutropenia.


  • Do not confuse rifaximin with rifampin.
  • PO Administer with or without food.

Patient/Family Teaching

  • Instruct patient to take rifaximin as directed and to complete therapy, even if feeling better. Caution patient to stop taking rifaximin if diarrhea symptoms get worse, persist more than 24–48 hr, or are accompanied by fever or blood in the stool. Consult health care professional if these occur. Advise patient not to treat diarrhea without consulting health care professional. May occur up to several wk after discontinuation of medication.
  • May cause dizziness. Caution patient to avoid driving and other activities requiring alertness until response to medication is known.
  • Rep:  Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

Evaluation/Desired Outcomes

  • Decreased severity of travelers' diarrhea.
  • Reduction in risk of overt hepatic encephalopathy recurrence.
  • Reduction in symptoms of irritable bowel syndrome with diarrhea.