Lumefantrine and Mefloquine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Lumefantrine
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
Reduced lumefantrine exposure and an increased risk of QT interval prolongation
Interaction Deep Dive
Avoid coadministration of artemether/lumefantrine and drugs that prolong QT interval, such as mefloquine as it may cause prolonged QT interval. If concomitant administration of artemether/lumefantrine and QT prolonging agent is medically required, monitor the ECG. Additionally, caution is advised when administering mefloquine after completing artemether/lumefantrine therapy due to the long half-life of lumefantrine (3 to 6 days). Concomitant use of artemether/lumefantrine and mefloquine may also result in reduced lumefantrine exposure. Therefore, instruct patients to take artemether/lumefantrine with food and monitor for reduced efficacy1.
Why it happens (mechanism)
Lower absorption secondary to a mefloquine-induced reduction in bile production; additive QT interval prolongation
Literature reports
2 reports — tap to read
a) The oral administration of mefloquine in 14 healthy volunteers administered as 3 doses of 500 mg, 250 mg, and 250 mg, followed 12 hours later by 6 doses of 4 tablets of 20 mg artemether/120 mg lumefantrine per tablet, had no effect on plasma concentrations of artemether or the artemether/DHA ratio. In the same study, there was a 30% reduction in C and 40% reduction in AUC of lumefantrine, possibly due to lower absorption secondary to a mefloquine-induced decrease in bile production 1.
b) Plasma concentrations of lumefantrine were reduced significantly (by one-third) when fixed artemether/lumefantrine was given concurrently with mefloquine in healthy subjects. The pharmacokinetics of artemether, dihydroartemisinin (active artemether metabolite), or mefloquine were not affected. Considering the wide range of lumefantrine plasma levels observed clinically during initiation of artemether/lumefantrine therapy, the significance of this interaction is doubtful, especially if lumefantrine is given with food, which significantly increases bioavailability. Confirmation of this interaction in falciparum malaria patients who have GI symptoms and altered absorption is required 2.
Common questions
Can I take Lumefantrine and Mefloquine together?
Reduced lumefantrine exposure and an increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Lumefantrine 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 "delayed". Effects tend to build up gradually over days to weeks.
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 Lumefantrine 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 (2)
- Product Information: COARTEM® oral tablets, artemether lumefantrine oral tablets. Novartis Pharmaceuticals Corporation (per DailyMed), East Hanover, NJ, 2025. DailyMed
- Lefevre G, Bindschedler M, Ezzet F, et al: Pharmacokinetic interaction between co-artemether and mefloquine. Eur J Pham Sci 2000; 10:141-151.
Keep reading about Lumefantrine
Keep reading about Mefloquine
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