Drug Interaction Report

Azathioprine and Mycophenolic Acid: Interaction Details

A pharmacist-reviewed analysis of the Azathioprine and Mycophenolic Acid interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Azathioprine

Azasan Azasan® Imuran Imuran®
+

Mycophenolic Acid

Myfortic
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Jul 11, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
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.

Of 219 documented Azathioprine interactions, 213 are rated major — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
delayed
Evidence
theoretical
Severity
Major

What happens

Greater inhibition of purine metabolism

Interaction Deep Dive

Mycophenolic acid or mycophenolic sodium and azathioprine should not be administered concomitantly due to inhibition of purine metabolism that both agents cause12.

Why it happens (mechanism)

Similar inhibition of purine metabolism

Common questions

Can I take Azathioprine and Mycophenolic Acid together?

Greater inhibition of purine metabolism Always confirm with your pharmacist or prescriber before making any change.

How serious is the Azathioprine and Mycophenolic Acid interaction?

It is rated major. Potentially serious — often needs a change or close monitoring.

How quickly could this interaction happen?

The documented onset is "delayed". Effects tend to build up gradually over days to weeks.

How strong is the evidence for this interaction?

The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

Questions for your pharmacist

  • Does my dose of Azathioprine or Mycophenolic Acid 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 (2)

  1. Product Information: Myfortic(R), mycophenolic acid delayed-release tablets. Novartis Pharmaceuticals Corporation, East Hanover, NJ, 2004. DailyMed
  2. Product Information: CELLCEPT(R) oral capsules, oral tablets, oral suspension, IV injection, mycophenolate mofetil oral capsules, oral tablets, oral suspension, IV injection. Roche Laboratories,Inc, Nutley, NJ, 2005. DailyMed
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Azathioprine

Keep reading about Azathioprine

All Azathioprine interactions (219) Azathioprine drug information
Also serious with: Febuxostat Atovaquone Peginterferon Alfa-2A Injection Acarbose
Mycophenolic Acid

Keep reading about Mycophenolic Acid

All Mycophenolic Acid interactions (19) Mycophenolic Acid drug information
Also serious with: Medroxyprogesterone Metronidazole Topical Metronidazole Metronidazole Injection
Beyond drug–drug

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:

Azathioprine + Activated Charcoal Beer Siberian Cocklebur Wine Active Hexose Correlated Compound (ahcc) Alfalfa American Ginseng Andrographis + 98 more
Mycophenolic Acid + Activated Charcoal Coffee Charcoal European Mandrake Glucomannan Guar Gum Gum Arabic Slippery Elm Tragacanth + 9 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.