Drug Interaction Report

Mefloquine and Ibutilide: Interaction Details

Name: Mefloquine and Ibutilide Interaction
Creator: Dr. Brian Staiger, PharmD, BCPS

A pharmacist-reviewed analysis of the Mefloquine and Ibutilide 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

Mefloquine

Lariam®

Ibutilide

Corvert

Medically reviewed by

Dr. Brian Staiger, PharmD, BCPS

Updated Aug 8, 2026

Editorial policy · Data sources

Interaction severity

Major

Potentially serious — often needs a change or close monitoring.

Minor

Moderate

Major

Contraindicated

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 256 documented Mefloquine interactions, 236 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 cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest)

Interaction Deep Dive

Even though no formal drug interaction studies have been done, concomitant use of Class III antiarrhythmic agents and drugs known to prolong the QT interval is not recommended²³. Cases of QTc prolongation and/or torsades de pointes have been reported with all Class III antiarrhythmic agents, including acecainide ⁴, amiodarone ⁵, azimilide ⁶, bretylium ⁷, ibutilide ⁸, sematilide ⁹, dofetilide ¹⁰, and sotalol ¹¹. Mefloquine was associated with significant QT prolongation in a study of 46 healthy subjects ¹.

Why it happens (mechanism)

Additive effects on QT prolongation

Common questions

Can I take Mefloquine and Ibutilide together?

An increased risk of cardiotoxicity (QT prolongation, torsades de pointes, cardiac arrest) Always confirm with your pharmacist or prescriber before making any change.

How serious is the Mefloquine and Ibutilide 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 Mefloquine or Ibutilide 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 (11)

Davis TME, Dembo LG, & Kaye-Eddie SA: Neurological, cardiovascular and metabolic effects of mefloquine in healthy volunteers: a double-blind, placebo-controlled trial. Br J Clin Pharmacol 1996; 42:415-421. PubMed
Product Information: Tikosyn(TM) dofetilide capsules. Pfizer Inc, New York, NY, 1999.
Product Information: Corvert(R), ibutilide fumarate injection. Upjohn Company, Kalamazoo, MI, 1998. DailyMed
Chow MJ, Piergies AA, Bowsher DJ, et al: Torsade de pointes induced by N-acetylprocainamide. J Am Coll Cardiol 1984; 4:621-624. PubMed
Faggiano P, Gardini A, D'Aloia A, et al: Torsade de pointes occurring early during oral amiodarone treatment. Int J Cardiol 1996; 55(2):205-208. DOI
Corey AE, Agnew JR, Valentine SN, et al: Azimilide pharmacokinetics following intravenous and oral administration of a solution and capsule formulation. J Clin Pharmacol 1999; 39(12):1272-1276. PubMed
Gilman AG, Goodman LS, Rall TW, et alGilman AG, Goodman LS, Rall TW, et al (Eds): The Pharmacological Basis of Therapeutics, 7th. Macmillan Publishing Co, New York, NY, 1985.
Rodriguez I, Kilborn MJ, Liu XK, et al: Drug-induced QT prolongation in women during the menstrual cycle. JAMA 2001; 285(10):1322-1326. PubMed
Singh BN: The coming of age of the class III antiarrhythmic principle: retrospective and future trends. Am J Cardiol 1996; 78(suppl):17-27. DOI
Allen MJ, Oliver SD, Newgreen MW, et al: Pharmacodynamic effect of continuous vs intermittent dosing of dofetilide on QT interval. Br J Clin Pharmacol 2002; 53:59-65.
Marill KA & Runge T: Meta-analysis of the risk of torsades de pointes in patients treated with intravenous racemic sotalol. Acad Emerg Med 2001; 8(2):117-124. PubMed

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Mefloquine

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All Mefloquine interactions (256) Mefloquine drug information

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Ibutilide

Keep reading about Ibutilide

All Ibutilide interactions (59)

Also serious with: Olodaterol Oral Inhalation Moxifloxacin Injection Deutetrabenazine Oxaliplatin Injection

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:

Mefloquine + Activated Charcoal Biofeedback Coffee Charcoal Dendrobium European Mandrake Ginkgo Glucomannan Guar Gum + 15 more

Ibutilide + Activated Charcoal American Hellebore Arsenic Cesium Ephedra Grapefruit Sida Cordifolia Bitter Orange + 22 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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About our interaction database: depth, not breadth

HelloPharmacist doesn't license one of the big commercial interaction databases, so what you'll find here is not a complete list of every known drug interaction. Instead, each entry is researched, analyzed, and written up individually — documented from the published literature, reviewed by a pharmacist, and cited so you can check every source yourself.

If a combination isn't listed here, it means we haven't documented it yet — never that it's safe. For screening a full medication list, we recommend pairing this site with a comprehensive tool like the Drugs.com Interaction Checker and, most importantly, a review by your own pharmacist. For a deep, plain-English, fully sourced explanation of a specific documented interaction — that's exactly what we built this for.

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.