Memantine and Hydrochlorothiazide: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Hydrochlorothiazide
Memantine
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
Altered plasma levels of memantine and hydrochlorothiazide
Interaction Deep Dive
Altered plasma levels of memantine and hydrochlorothiazide may result with coadministration of drugs that use the same renal cationic system, including memantine and hydrochlorothiazide. Coadministration of memantine with hydrochlorothiazide decreased the bioavailability of hydrochlorothiazide by 20%12.
Why it happens (mechanism)
Common renal cationic system elimination pathway
Common questions
Can I take Memantine and Hydrochlorothiazide together?
Altered plasma levels of memantine and hydrochlorothiazide Always confirm with your pharmacist or prescriber before making any change.
How serious is the Memantine and Hydrochlorothiazide interaction?
It is rated moderate. Can be significant — usually manageable with 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.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Memantine or Hydrochlorothiazide 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)
- Product Information: Namenda(R) oral tablets, solution, memantine hydrochloride oral tablets, solution. Forest Pharmaceuticals Inc, St Louis, MO, 2007. DailyMed
- Product Information: NAMENDA XR(R) extended release oral capsules, memantine hydrochloride extended release oral capsules. Forest Pharmaceuticals, Inc, New York, NY, 2010.
Keep reading about Hydrochlorothiazide
Keep reading about Memantine
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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