Lofexidine and Mefloquine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Lofexidine
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 risk of QT interval prolongation
Interaction Deep Dive
Treatment with lofexidine may prolong the QT interval. In patients maintained on buprenorphine or methadone (medications that may prolong the QT interval), the addition of lofexidine resulted in an increase in QTcF of 15 and 9.1 milliseconds, respectively. Monitor ECG in patients taking concomitant QT prolonging drugs1.
Why it happens (mechanism)
Additive QT interval prolongation
Literature reports
2 reports — tap to read
a) In a study of 18 patients maintained on methadone (80 to 120 mg/day), coadministration with lofexidine (2.88 mg/day) resulted in a maximum mean increase in QTcF from methadone-alone baseline of 9.1 milliseconds 1.
b) In a study of 21 patients maintained on buprenorphine (16 to 24 mg/day), coadministration with lofexidine (2.88 mg/day) resulted in a maximum mean increase in QTcF from buprenorphine-alone baseline of 15 milliseconds 1.
Common questions
Can I take Lofexidine and Mefloquine together?
Increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Lofexidine 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 "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Lofexidine 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: LUCEMYRA(TM) oral tablets, lofexidine oral tablets. US WorldMeds LLC (per FDA), Louisville, KY, 2018. DailyMed
Keep reading about Lofexidine
Keep reading about Mefloquine
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:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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