Drug Interaction Report

Nifedipine and Primidone: Interaction Details

A pharmacist-reviewed analysis of the Nifedipine and Primidone 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

Primidone

Mysoline
+

Nifedipine

Adalat® Adalat® CC Afeditab CR Afeditab® CR Nifedical® XL Nifeditab® CR Procardia Procardia®
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
Contraindicated
These should generally not be used together.
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 325 documented Nifedipine interactions, 17 are rated contraindicated — 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
established
Severity
Contraindicated

What happens

Reduced NIFEdipine exposure

Interaction Deep Dive

Coadministration of NIFEdipine and PHENobarbital or primidone (prodrug of PHENobarbital) (strong CYP3A4 inducer) is contraindicated, as concomitant use may significantly reduce NIFEdipine efficacy1. Consider alternate antihypertensive therapy 21.

Why it happens (mechanism)

Induction of CYP3A4-mediated metabolism of NIFEdipine

Common questions

Can I take Nifedipine and Primidone together?

Reduced NIFEdipine exposure Always confirm with your pharmacist or prescriber before making any change.

How serious is the Nifedipine and Primidone interaction?

It is rated contraindicated. These should generally not be used together.

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 Nifedipine or Primidone 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: NIFEDIPINE oral tablet, extended-release, nifedipine oral tablet, extended-release. Aurobindo Pharma Limited (per DailyMed), East Windsor, NJ, 2024. DailyMed
  2. Product Information: PROCARDIA XL(R) oral extended-release tablets, nifedipine oral extended-release tablets. Pfizer Labs (per Dailymed), New York, NY, 2023. DailyMed
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Primidone

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All Primidone interactions (204)
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Nifedipine

Keep reading about Nifedipine

All Nifedipine interactions (325) Nifedipine drug information
Also serious with: Rifampin Rifabutin St John's Wort Rifapentine
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:

Primidone + 1,4-butanediol Activated Charcoal Beer Gamma-hydroxybutyrate (ghb) Kava L-tryptophan Wine 5-htp + 116 more
Nifedipine + Activated Charcoal American Hellebore American Mistletoe Beer Coca Coleus Grapefruit Siberian Cocklebur + 265 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.