Drug Interaction Report

Viloxazine and Mexiletine: Interaction Details

A pharmacist-reviewed analysis of the Viloxazine and Mexiletine 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

Mexiletine

Mexitil®
+

Viloxazine

Qelbree Qelbree®
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 10 documented Viloxazine interactions, 2 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
probable
Severity
Contraindicated

What happens

Increased exposure of CYP2D6 substrates that are CYP1A2 sensitive or NTI substrates and an increased risk of CYP2D6 substrates that are CYP1A2 sensitive or NTI substrate-related adverse reaction

Interaction Deep Dive

Concomitant use of viloxazine (strong CYP1A2 inhibitor) and CYP2D6 substrates that also are CYP1A2 sensitive or NTI substrates is contraindicated due to a significant increase in total exposure of substrates, which may also increase the risk of substrates-related adverse reactions. If coadministration is needed, monitor patients for adverse reactions and adjust dosages of CYP2D6 substrates, as needed1.

Why it happens (mechanism)

Inhibition of CYP2D6-substrate metabolism by viloxazine; inhibition of CYP1A2-substrate metabolism by viloxazine

Literature reports

2 reports — tap to read

a) In a drug interaction study, coadministration of viloxazine with dextromethorphan (CYP2D6 substrate) led to increased Cmax and AUC by approximately 1.6-fold and 1.9-fold, respectively 1.

b) In a drug interaction study, coadministration of viloxazine with caffeine (CYP1A2 substrate) led to increased Cmax and AUC by approximately 1-fold and 5.9-fold, respectively 1.

Common questions

Can I take Viloxazine and Mexiletine together?

Increased exposure of CYP2D6 substrates that are CYP1A2 sensitive or NTI substrates and an increased risk of CYP2D6 substrates that are CYP1A2 sensitive or NTI substrate-related adverse reaction Always confirm with your pharmacist or prescriber before making any change.

How serious is the Viloxazine and Mexiletine 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 "probable". Good supporting evidence, though not definitively proven.

Questions for your pharmacist

  • Does my dose of Viloxazine or Mexiletine 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 (1)

  1. Product Information: QELBREE(TM) oral extended-release capsules, viloxazine oral extended-release capsules. Supernus Pharmaceuticals Inc (per FDA), Rockville, MD, 2022. DailyMed
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Mexiletine

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Viloxazine

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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:

Mexiletine + Activated Charcoal 1,3-dmaa Acacia Rigidula Active Hexose Correlated Compound (ahcc) Adrafinil African Wild Potato Ashitaba Ayahuasca + 144 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.