Drug interactions
Metolazone + Tolvaptan
Severity: Moderate
Metolazone and Tolvaptan: 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
Both drugs promote fluid loss, so combined use can cause excessive diuresis, dehydration, hypotension and electrolyte disturbances. Tolvaptan can also cause rapid rises in serum sodium, and a thiazide may add to this effect.
What this interaction means in plain words
Metolazone and Tolvaptan 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; Tolvaptan belongs to Endocrine.
Why it happens
Additive diuretic effects: tolvaptan aquaresis via V2 receptor antagonism plus metolazone natriuresis.
What to do
Monitor serum sodium frequently, especially during the first 24 to 48 hours, along with volume status and renal function. Reduce or stop the diuretic if sodium correction is too rapid or hypovolemia 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 Tolvaptan
- Atazanavir + Tolvaptan Contraindicated
- Ceritinib + Tolvaptan Contraindicated
- Cobicistat + Tolvaptan Contraindicated
- Conivaptan + Tolvaptan Contraindicated
- Darunavir + Tolvaptan Contraindicated
- Idelalisib + Tolvaptan Contraindicated
Frequently asked questions
Can I take Metolazone with Tolvaptan?
MediHelp rates the interaction as moderate. Metolazone and Tolvaptan 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. Both drugs promote fluid loss, so combined use can cause excessive diuresis, dehydration, hypotension and electrolyte disturbances. Tolvaptan can also cause rapid rises in serum sodium, and a thiazide may add to this effect.
How serious is the interaction between Metolazone and Tolvaptan?
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 serum sodium frequently, especially during the first 24 to 48 hours, along with volume status and renal function. Reduce or stop the diuretic if sodium correction is too rapid or hypovolemia 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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