Rifampin and Moxifloxacin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Moxifloxacin
Rifampin
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Reduced moxifloxacin exposure
Interaction Deep Dive
Exert caution with coadministration of rifAMPin with drugs metabolized by cytochrome P450, such as moxifloxacin1. An open-label, multiple-dose, pharmacokinetic study in tuberculosis patients (n=19) demonstrated reductions in moxifloxacin exposure and plasma levels when used concomitantly with rifAMPin 2. Concomitant use of rifAMPin with moxifloxacin may reduce exposure of moxifloxacin 34.
Why it happens (mechanism)
Induction of uridine diphosphate glucuronosyltransferase and sulfotransferase metabolism of moxifloxacin by rifAMPin
Literature reports
1 report — tap to read
a) The AUC and Cmax of moxifloxacin decreased by 31% and 32%, respectively, when moxifloxacin was combined with intermittently administered rifAMPin and isoniazid in 19 Indonesian patients with tuberculosis (TB) in an open-label, multiple-dose, pharmacokinetic study. The mean weight of the patients was 55 kg (range, 38 to 80 kg). During their last month of treatment with 600 mg of isoniazid and 450 mg of rifAMPin, moxifloxacin 400 mg once daily for 5 days was added (phase I). After a 1-month washout, patients received 400 mg of oral moxifloxacin alone every day for another 5 days. The following are the geometric means (range) of moxifloxacin for phase I and phase II, respectively, for: AUC (0 to 24 hour (hr)), 33.3 milligrams x hour/liter (mg x hr/L) and 48.2 mg x hr/L; Cmax, 3.2 mg/L and 4.7 mg/L; total clearance, 12 L/hr (7.2 to 16 L/hr) and 8.3 L/hr (6.6 to 10.8 L/hr); and half-life, 7.1 hr and 9.9 hr. The corresponding geometric ratios (90% confidence interval) between the 2 phases were 0.69 (0.65 to 0.74) for AUC, 0.68 for Cmax, 1.45 for total clearance, and 0.72 for half-life. Additionally, moxifloxacin Tmax was prolonged when combined with rifAMPin and isoniazid. The geometric mean values for AUC: minimum inhibitory concentration (MIC) and Cmax: MIC for moxifloxacin in phase II were significantly higher (p less than 0.01) and approached the desired value compared with phase I. The AUC: MIC was greater than 100 (target ratio) in 47% of patients in the phase II compared with 5% of patients in phase I 2.
Common questions
Can I take Rifampin and Moxifloxacin together?
Reduced moxifloxacin exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Rifampin and Moxifloxacin interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "established". Well documented — supported by controlled studies or strong clinical data.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Rifampin or Moxifloxacin need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (4)
- Product Information: RIFATER(R) oral tablets, rifampin, isoniazid, pyrazinamide oral tablets. sanofi-aventis US LLC (per FDA), Bridgewater, NJ, 2023. DailyMed
- Nijland HM, Ruslami R, Suroto AJ, et al: Rifampicin reduces plasma concentrations of moxifloxacin in patients with tuberculosis. Clin Infect Dis 2007; 45(8):1001-1007. PubMed
- Product Information: RIFADIN(R) IV intravenous injection, rifampin intravenous injection. sanofi-aventis US LLC (per FDA), Bridgewater, NJ, 2023. DailyMed
- Product Information: RIFADIN(R) oral capsules, rifampin oral capsules. sanofi-aventis US LLC (per FDA), Bridgewater, NJ, 2023. DailyMed
Keep reading about Moxifloxacin
Keep reading about Rifampin
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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