Metronidazole and Mycophenolate Mofetil: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Metronidazole
Mycophenolate Mofetil
No brand names on record
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
Decreased mycophenolate plasma exposure and possible reduced efficacy
Interaction Deep Dive
Concomitant administration of mycophenolate mofetil and the combination of metronidazole and norfloxacin resulted in significant decreases in mycophenolate plasma exposure due to interference with enterohepatic recirculation. Monitor patients for alterations in efficacy when these drugs are coadministered. Obtaining mycophenolic acid (MPA) plasma levels before and after the initiation or discontinuation of concomitant medications may be necessary to ensure MPA levels remain stable1.
Why it happens (mechanism)
Interference with enterohepatic recirculation of mycophenolic acid
Literature reports
1 report — tap to read
a) In healthy volunteers (n=11), a singe-dose of mycophenolate mofetil 1 g on day 4 of a 5-day course of a combination of metronidazole and norfloxacin resulted in a significant 33% decrease in the mean mycophenolic acid exposure (AUC (0 to 48 hours)) compared with administration of mycophenolate mofetil alone. Upon concomitant administration of mycophenolate mofetil with metronidazole or norfloxacin separately, there was no significant effect on mycophenolate mofetil exposure. The mean AUC(0 to 48 hours) of mycophenolate mofetil was 42.7 +/- 23 mcg x hr/mL with coadministration with metronidazole and 48.3 +/- 24 mcg x hr/mL with coadministration with norfloxacin compared with 56.2 +/- 24 mcg x hr/mL when mycophenolate mofetil was administered alone 1.
Common questions
Can I take Metronidazole and Mycophenolate Mofetil together?
Decreased mycophenolate plasma exposure and possible reduced efficacy Always confirm with your pharmacist or prescriber before making any change.
How serious is the Metronidazole and Mycophenolate Mofetil 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 Metronidazole or Mycophenolate Mofetil 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 (1)
- Product Information: CELLCEPT(R) oral capsules, oral tablets, oral suspension, intravenous injection, mycophenolate mofetil oral capsules, oral tablets, oral suspension, intravenous injection. Genentech USA, Inc (per FDA), South San Francisco, CA, 2019. DailyMed
Keep reading about Metronidazole
Keep reading about Mycophenolate Mofetil
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist