Drug Interaction Report

Leflunomide and Mumps Virus Vaccine, Live: Interaction Details

A pharmacist-reviewed analysis of the Leflunomide and Mumps Virus Vaccine, Live interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Leflunomide

Arava Arava®
+

Mumps Virus Vaccine, Live

No brand names on record
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 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 58 documented Leflunomide interactions, 52 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
unspecified
Evidence
theoretical
Severity
Major

What happens

An increased risk of secondary transmission of infection by the live vaccine and reduced effectiveness of immunization

Interaction Deep Dive

Although data are not available on the effects of concurrent vaccination, the administration of live vaccines is not recommended during treatment with leflunomide1. Consider delaying vaccination until at least 6 months after therapy has been discontinued 2.

Why it happens (mechanism)

Altered cellular immune response

Common questions

Can I take Leflunomide and Mumps Virus Vaccine, Live together?

An increased risk of secondary transmission of infection by the live vaccine and reduced effectiveness of immunization Always confirm with your pharmacist or prescriber before making any change.

How serious is the Leflunomide and Mumps Virus Vaccine, Live 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 "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

Questions for your pharmacist

  • Does my dose of Leflunomide or Mumps Virus Vaccine, Live 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: ARAVA(R) oral tablets, leflunomide oral tablets. Sanofi-Aventis U.S. LLC (per FDA), Bridgewater, NJ, 2012. DailyMed
  2. Product Information: AUBAGIO(R) oral tablets, teriflunomide oral tablets. Genzyme Corporation, Cambridge, MA, 2012. DailyMed
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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:

Leflunomide + Activated Charcoal Beer Siberian Cocklebur Wine Ashwagandha Black Cohosh Boldo Buchu + 51 more

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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.