Rifaximin
XIFAXAN
Pronunciation: ri-FAX-i-men
“Xi the Rye faxin’ man”
Nonabsorbed gut-directed rifamycin
What it isMinimally absorbed RNA-polymerase-inhibiting rifamycin; hepatic encephalopathy, IBS with diarrhea, and travelers' diarrhea.
Why this oneIt acts almost entirely in the gut, avoiding the systemic toxicity and enzyme induction associated with rifampin.
What limits itCost is the main barrier. For hepatic encephalopathy it is generally added to lactulose rather than replacing it.
FDA-approved for
- travelers diarrhea/IBS-D/HE (2004)
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Travelers' diarrhea (noninvasive E. coli) | adults & ≥12 yr | 200 mg TID x3 days | 200 mg TID x3 days | 200 mg TID x3 days |
| Hepatic encephalopathy (recurrence reduction) | adult | 550 mg BID | 550 mg BID | 550 mg BID |
| Irritable bowel syndrome with diarrhea (IBS-D) | adult | 550 mg TID x14 days | 550 mg TID x14 days | 550 mg TID x14 days |
Renal Undefined (not studied)
Hepatic No dosage adjustment recommended; use with caution in severe (Child-Pugh C)
IBS-D: recurrence may be retreated up to two times with the same regimen
Instructions
- With or without food
Available strengths
- tab 200, 550 mg
Cautions
- Not effective for travelers' diarrhea with fever/bloody stool or non-E. coli pathogens; discontinue if symptoms worsen or persist >24-48 h
- C. difficile-associated diarrhea
- Caution in severe (Child-Pugh C) hepatic impairment (increased exposure)
- P-glycoprotein inhibitors (e.g., cyclosporine) substantially increase systemic exposure
- Severe cutaneous adverse reactions (SJS, TEN) in cirrhosis
Adverse reactions
- TD: headache
- HE: peripheral edema, nausea, dizziness, fatigue, ascites, pruritus
- IBS-D: increased ALT, nausea
Pregnancy No human data; teratogenic in animals — advise of potential fetal risk
Lactation Undefined
Cost
| Strength | #/mo | generic $/mo | CostPlus | |
|---|---|---|---|---|
| 200 mg | tab | 90 TID | not offered | |
| 550 mg | tab | 90 TID | not offered |
Generic entry2029 est.
NO BOXED WARNINGS
Principal riskLittle; minimal absorption
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityLocal irritation or hypersensitivity; systemic toxicity is minimal with correct local use.
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