Mycophenolate Mofetil and Amoxicillin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Amoxicillin
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 mycophenolic acid plasma exposure
Interaction Deep Dive
Median trough mycophenolic acid (MPA; active metabolite of mycophenolate mofetil) concentration was reduced by about 50% from baseline at 3 days after introduction of amoxicillin/clavulanic acid. The reduction in exposure diminished within 14 days of antimicrobial therapy and ceased within 3 days of discontinuation of the antibiotic. When coadministration of mycophenolate mofetil plus amoxicillin/clavulanic acid is required, monitor patients for alterations in efficacy or mycophenolate mofetil-related adverse reactions. Obtaining 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)
Inhibition of enterohepatic recirculation of mycophenolic acid by amoxicillin/clavulanic acid
Literature reports
1 report — tap to read
a) In a study of kidney transplant recipients (N=64), ciprofloxacin 500 mg orally twice daily and amoxicillin with clavulanic acid 375 mg 3 times daily 2 were administered to two groups of patients (group 1 received 7 days of antibiotics; group 2 received at least 14 days of antibiotics). There was a significant decrease in MPA levels in both groups within 3 days of starting antibiotics (median day 3 level, 46% to 48% of baseline) with no further decrease in MPA level by day 7. In group 1, levels returned to normal 3 days after the completion of antibiotic therapy; in group 2, MPA levels on day 14 were significantly higher than on day 3 or day 7 (median day 14 level, 79% of baseline). No dosage adjustments of mycophenolate mofetil were done in either group. There was no significant difference in the effect on MPA levels between ciprofloxacin or amoxicillin with clavulanic acid. There were no deaths, graft losses, acute rejection episodes, or gastrointestinal adverse effects during antibiotic therapy 3.
Common questions
Can I take Mycophenolate Mofetil and Amoxicillin together?
Decreased mycophenolic acid plasma exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Mycophenolate Mofetil and Amoxicillin interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
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 Mycophenolate Mofetil or Amoxicillin 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 (3)
- 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
- 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, 2018. DailyMed
- Borrows R, Chusney G, Loucaidou M, et al: The magnitude and time course of changes in mycophenolic acid 12-hour predose levels during antibiotic therapy in mycophenolate mofetil-based renal transplantation. Ther Drug Monit 2007; 29(1):122-126. PubMed
Keep reading about Amoxicillin
Keep reading about Mycophenolate Mofetil
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