Valproic Acid and Mefloquine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Mefloquine
Valproic Acid
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
Loss of seizure control
Interaction Deep Dive
The concomitant use of mefloquine in patients taking an anticonvulsant may cause reduced seizure control by lowering plasma levels of the anticonvulsant2. One case report describes a male who experienced an increase in the frequency of his seizures after he was prescribed mefloquine for malaria prophylaxis. His antiepileptic medication included carbamazepine and sodium valproate. Pharmacokinetic studies determined that the half-life of sodium valproate was significantly reduced by the administration of mefloquine, while carbamazepine was not affected 1.
Why it happens (mechanism)
Unknown
Literature reports
1 report — tap to read
a) A 38-year old male with epilepsy controlled by carbamazepine 1200 mg daily and sodium valproate 1 gram daily was given mefloquine 250 mg weekly. The patient began to experience multiple partial seizures. The pharmacokinetics of the antiepileptic drugs were studied to determine the cause of this patient's seizures. A reduction in the half-life of sodium valproate (from 8-20 hours to 5.6 hours) was observed, although that of carbamazepine was unchanged. It is possible that mefloquine accelerated the metabolism of sodium valproate, since they both share the same hepatic metabolic mechanism 1.
Common questions
Can I take Valproic Acid and Mefloquine together?
Loss of seizure control Always confirm with your pharmacist or prescriber before making any change.
How serious is the Valproic Acid and Mefloquine interaction?
It is rated moderate. Can be significant — usually manageable with 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.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Valproic Acid 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 anything you'd monitor while I'm on both?
References (2)
Keep reading about Mefloquine
Keep reading about Valproic Acid
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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