Mexiletine and Lorcaserin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Lorcaserin
No brand names on recordMexiletine
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.
What happens
Increased mexiletine plasma concentrations
Interaction Deep Dive
In a clinical trial in 21 CYP2D6 extensive metabolizers, coadministration of lorcaserin, a CYP2D6 inhibitor, 10 mg twice a day for 4 days increased dextromethorphan, a CYP2D6 substrate, peak concentrations (Cmax) by approximately 76% and exposure (AUC) by approximately 2-fold2. Therefore the concomitant use of mexiletine, a CYP2D6 substrate 1, and lorcaserin may increase mexiletine plasma concentrations 2. Dose reduction of mexiletine may be required when coadministered with lorcaserin.
Why it happens (mechanism)
Inhibition of CYP2D6-mediated mexiletine metabolism by lorcaserin
Common questions
Can I take Mexiletine and Lorcaserin together?
Increased mexiletine plasma concentrations Always confirm with your pharmacist or prescriber before making any change.
How serious is the Mexiletine and Lorcaserin interaction?
It is rated moderate. Can be significant — usually manageable with 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 Mexiletine or Lorcaserin 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 anything you'd monitor while I'm on both?
References (2)
- Product Information: mexiletine HCl oral capsules, mexiletine HCl oral capsules. Watson Laboratories, Inc (per DailyMed), Corona, CA, 2006. DailyMed
- Product Information: BELVIQ(R) oral tablets, lorcaserin hydrochloride oral tablets. Eisai Inc. (per manufacturer), Woodcliff Lake, NJ, 2012.
Keep reading about Lorcaserin
Keep reading about Mexiletine
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
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