Drug Interaction Report

Dofetilide and Lamotrigine: Interaction Details

A pharmacist-reviewed analysis of the Dofetilide and Lamotrigine 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

Lamotrigine

Lamictal Subvenite
+

Dofetilide

Tikosyn Tikosyn®
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 454 documented Dofetilide interactions, 288 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

Increased dofetilide exposure

Interaction Deep Dive

Coadministration of lamoTRIgine (an OCT2 inhibitor) with OCT2 substrates with a narrow therapeutic index, such as dofetilide is not recommended due to the risk of dofetilide exposure12.

Why it happens (mechanism)

Inhibition of OCT2-mediated efflux transport of lamoTRIgine

Common questions

Can I take Dofetilide and Lamotrigine together?

Increased dofetilide exposure Always confirm with your pharmacist or prescriber before making any change.

How serious is the Dofetilide and Lamotrigine 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.

From our Q&A

Real reader questions about these medications, each personally answered by our pharmacist:

Questions for your pharmacist

  • Does my dose of Dofetilide or Lamotrigine 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: LAMICTAL(R) oral tablets, oral chewable dispersible tablets, lamotrigine oral tablets, oral chewable dispersible tablets. GlaxoSmithKline (per FDA), Research Triangle Park, NC, 2014. DailyMed
  2. Product Information: SUBVENITE® oral suspension, lamotrigine oral suspension. OWP Pharmaceuticals, Inc. (per FDA), Lisle, IL, 2025. DailyMed
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Lamotrigine

Keep reading about Lamotrigine

All Lamotrigine interactions (22)
Also serious with: Azathioprine Orlistat Methotrexate Injection Hydroxychloroquine
Dofetilide

Keep reading about Dofetilide

All Dofetilide interactions (454) Dofetilide drug information
Also serious with: Bictegravir Cimetidine Saquinavir Cisapride
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:

Lamotrigine + 1,4-butanediol Activated Charcoal Beer Gamma-hydroxybutyrate (ghb) Kava L-tryptophan Wine 5-htp + 108 more
Dofetilide + Activated Charcoal American Hellebore Arsenic Cesium Ephedra Grapefruit Sida Cordifolia St. John's Wort + 138 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.