Quinine and Mefloquine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Quinine
No brand names on recordMefloquine
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 mefloquine exposure and an increased risk of seizures, QT-interval prolongation, and torsade de pointes
Interaction Deep Dive
Concurrent use of mefloquine and quinine may result in increased mefloquine exposure and should be avoided. Concomitant use of mefloquine and quinine increases the risk of seizures and ECG abnormalities, including QTc prolongation, potentially causing serious ventricular arrhythmias such as torsade de pointes. In a study in healthy subjects (n=7), concurrent use of mefloquine and quinine increased mefloquine exposure by 22% and prolongation of the QTc interval was reported1.
Why it happens (mechanism)
Unknown
Literature reports
1 report — tap to read
a) In healthy subjects (n=7) who received mefloquine 750 mg 24 hours prior to a single dose of quinine sulfate 600 mg, the mefloquine AUC increased by 22% compared with mefloquine administered alone. The QTc interval was significantly prolonged in subjects who received mefloquine and quinine sulfate in this study 1.
Common questions
Can I take Quinine and Mefloquine together?
Increased mefloquine exposure and an increased risk of seizures, QT-interval prolongation, and torsade de pointes Always confirm with your pharmacist or prescriber before making any change.
How serious is the Quinine and Mefloquine 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 Quinine or Mefloquine 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)
- Product Information: QUALAQUIN(R) oral capsules, quinine sulfate oral capsules. AR Scientific, Inc. (per FDA), Philadelphia, PA, 2013. DailyMed
Keep reading about Quinine
Keep reading about Mefloquine
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