Drug interactions
Metolazone + Spironolactone
Severity: Moderate
Metolazone and Spironolactone: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
The combination produces strong sequential diuresis, and the potassium-sparing action of spironolactone offsets metolazone-induced potassium loss. Serum potassium can still fall or rise, and excessive diuresis may cause volume depletion, hyponatraemia and renal impairment.
What this interaction means in plain words
Metolazone and Spironolactone can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Metolazone belongs to Cardiovascular; Spironolactone belongs to Cardiovascular.
Why it happens
Complementary nephron-site diuretic effects with opposing potassium effects: metolazone blocks distal sodium chloride reabsorption and spironolactone antagonises aldosterone.
What to do
Monitor potassium, sodium, creatinine and weight closely after initiation and dose changes. Reduce doses if hypotension or electrolyte disturbance develops.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Metolazone
Other interactions of Spironolactone
- Amiloride + Spironolactone Contraindicated
- Eplerenone + Spironolactone Contraindicated
- Spironolactone + Triamterene Contraindicated
- Abiraterone + Spironolactone Major
- Aceclofenac + Spironolactone Major
- Acemetacin + Spironolactone Major
Frequently asked questions
Can I take Metolazone with Spironolactone?
MediHelp rates the interaction as moderate. Metolazone and Spironolactone can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. The combination produces strong sequential diuresis, and the potassium-sparing action of spironolactone offsets metolazone-induced potassium loss. Serum potassium can still fall or rise, and excessive diuresis may cause volume depletion, hyponatraemia and renal impairment.
How serious is the interaction between Metolazone and Spironolactone?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor potassium, sodium, creatinine and weight closely after initiation and dose changes. Reduce doses if hypotension or electrolyte disturbance develops.
What other medicines interact with Metolazone?
MediHelp also lists interactions of Metolazone with, for example, Amifostine, Amlodipine-hydrochlorothiazide-valsartan, Amlodipine-olmesartan-hydrochlorothiazide. The full list is on the Metolazone page.
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