Drug Interaction Report

Methazolamide and Topiramate: Interaction Details

A pharmacist-reviewed analysis of the Methazolamide and Topiramate 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

Topiramate

Eprontia Qudexy Topamax Trokendi
+

Methazolamide

Neptazane®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
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 10 documented Methazolamide interactions, 10 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
probable
Severity
Major

What happens

An increased risk of nephrolithiasis and severity of metabolic acidosis

Interaction Deep Dive

Topiramate (a carbonic anhydrase inhibitor) used concomitantly with another carbonic anhydrase inhibitor should be avoided1. The combination of carbonic anhydrase inhibitors may increase the risk of renal stone formation and the severity of metabolic acidosis. If concomitant use is unavoidable, monitor the patient for the appearance or worsening of metabolic acidosis 2.

Why it happens (mechanism)

Additive effects of carbonic anhydrase inhibition

Literature reports

1 report — tap to read

a) In a study of 15 patients with drug refractory partial epilepsy or Lennox-Gastaut syndrome, subjects were placed on topiramate in addition to their previous antiepileptic drug regimens. One patient passed a renal stone during the study, which is consistent with the documented increased risk of nephrolithiasis 3.

Common questions

Can I take Methazolamide and Topiramate together?

An increased risk of nephrolithiasis and severity of metabolic acidosis Always confirm with your pharmacist or prescriber before making any change.

How serious is the Methazolamide and Topiramate 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 Methazolamide or Topiramate 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 (3)

  1. Product Information: QSYMIA(R) oral extended-release capsules, phentermine topiramate oral extended-release capsules. VIVUS LLC (per FDA), Campbell, CA, 2022. DailyMed
  2. Product Information: TOPAMAX(R) oral tablets, oral sprinkle capsules, topiramate oral tablets, oral sprinkle capsules. Janssen Pharmaceuticals Inc (per FDA), Titusville, NJ, 2023. DailyMed
  3. Tartara A, Sartori I, Manni R, et al: Efficacy and safety of topiramate in refractory epilepsy: a long-term prospective trial. Ital J Neurol Sci 1996; 17:429-432. PubMed
Was this write-up helpful?
Topiramate

Keep reading about Topiramate

All Topiramate interactions (51)
Also serious with: Cariprazine Orlistat Hydromorphone Rectal Lumateperone
Methazolamide

Keep reading about Methazolamide

All Methazolamide interactions (10) Methazolamide drug information
Also serious with: Aspirin Aspirin Rectal Azathioprine Memantine
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:

Topiramate + 1,4-butanediol Activated Charcoal Beer Gamma-hydroxybutyrate (ghb) Kava L-tryptophan Wine 5-htp + 117 more
Methazolamide + Activated Charcoal American Hellebore American Mistletoe Lithium Oleander Tyramine Yellow Dock Abuta + 210 more

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

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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.