Cyclosporine
Moderate
Database
Despite minimal absorption, rifaximin may increase cyclosporine levels via P-gp inhibition in gut
Monitor cyclosporine levels when co-prescribing
Source: Kimi deep-research + Cla
Drug reference
Rifaximin
Rifamycin-derived antibiotic (non-aminoglycoside, non-systemic) · Antibiotic
Also known as Rifaximin alfa
START
Traveler's diarrhea: 200 mg TDS x 3 days. HE: 550 mg BD ongoing. IBS-D: 550 mg TDS x 14 days
TYPICAL MAX
1650 mg/day
STOP IF
Bloody diarrhea, fever (suggests invasive pathogen), severe allergic reaction
WATCH
Diarrhea characteristics (ensure non-invasive), response to treatment, C. difficile if recurrent diarrhea
CDSCO approvedSchedule HATC A07AA11
KDIGO 2024 + manufacturer label
- ONSET
- 23min · absorption onset
- PEAK
- 1.5h · Minimal systemic peak
- t½
- 6h · Systemic half-life (irrelevant - local action)
- DURATION
- 1d · Duration of gut transit provides coverage
EXCRETION
Fecal (>97%, mostly unchanged)
route + CYP
INTERACTIONS
—
none in our sources
PREGNANCY
Animal studies show no harm; limited human data - use if benefits outweigh risks
FDA category + note
Available in India
322 branded formulations. Look up specific brands in the Drugs workspace.
Mechanism
Binds to beta-subunit of bacterial DNA-dependent RNA polymerase, inhibiting transcription and protein synthesis. Bactericidal against Gram-positive and Gram-negative aerobes and anaerobes. Poor oral absorption results in high gut lumen concentrations with minimal systemic exposure.
Indications
Traveler's diarrhea (non-invasive E. coli)Hepatic encephalopathy (prevention of recurrence)Irritable bowel syndrome with diarrhea (IBS-D)Small intestinal bacterial overgrowth (SIBO) - off-label
Dosing
- Adult
- Traveler's diarrhea: 200 mg TDS for 3 days. Hepatic encephalopathy: 550 mg BD. IBS-D: 550 mg TDS for 14 days
- Pediatric
- >12 years: 200 mg TDS for 3 days (traveler's diarrhea); <12 years: not recommended
- Renal adjustment
- No adjustment needed; minimal systemic absorption
- Hepatic adjustment
- No adjustment needed; minimal systemic exposure
- Geriatric
- Standard dosing
- Max dose
- 1650 mg/day (550 mg TDS)
Pharmacokinetics
Onset
24-48 hours (symptom improvement)
Peak effect
1-2 hours (Tmax for minimal systemic absorption)
Duration
Duration of gut transit
Half-life
~6 hours (systemic; minimal relevance due to local action)
Bioavailability
<0.4% (virtually non-absorbed)
Protein binding
67.5%
Metabolism
Minimal systemic metabolism; locally metabolized in gut
Excretion
Fecal (>97% unchanged)
Contraindications
- Hypersensitivity to rifamycins (rifampicin, rifabutin, rifapentine)
- Diarrhea with bloody stools or fever (suspected invasive pathogens)
Side effects
Common
NauseaFlatulenceAbdominal painConstipationHeadachePeripheral edema (hepatic encephalopathy dosing)
Serious
- C. difficile-associated diarrhea
- Severe allergic reactions (rare)
- Angioedema (rare)
- Anaphylaxis (rare)
Pregnancy & lactation
Pregnancy
Animal studies show no harm; limited human data - use if benefits outweigh risks
Lactation
Minimal systemic absorption makes transfer to breast milk unlikely; compatible with breastfeeding
Drug interactions
11 additional unreviewed or low-confidence interactions hidden because their provenance or source detail is insufficient.
Related guidelines
Irritable bowel syndrome
ISG · Gastroenterology · 2023
Empirical antimicrobial use in common syndromes
ICMR · Infectious Diseases · 2019
Infective endocarditis prevention
ADA_DENTAL · Dentistry · 2015
Inflammatory bowel disease
OTHER · Gastroenterology · 2015
Acute liver failure
ICMR · Gastroenterology · 2022
Ask House about Rifaximin
Continue into a citation-backed clinical answer with the drug context already attached.
Textbook-sourced·Sources: Goodman & Gilman 14e, Katzung, BNF, Nelson·Updated: 2026-05-19·Cockpit curated: 2026-05-19