Drug interactions
Metolazone + Sulfamethoxazole
Severity: Moderate
Metolazone and Sulfamethoxazole: 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 thiazide-type diuretics and sulfamethoxazole-trimethoprim can lower serum sodium, and the combination may increase hyponatremia risk, especially in older adults. Hyperkalemia from trimethoprim may partly offset diuretic potassium loss.
What this interaction means in plain words
Metolazone and Sulfamethoxazole 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.
Why it happens
Additive effects on sodium handling: diuretic-induced sodium loss plus trimethoprim blockade of distal tubular sodium channels.
What to do
Monitor serum sodium and potassium within the first week of combined therapy, particularly in elderly patients, and stop or change therapy if significant hyponatremia 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
Frequently asked questions
Can I take Metolazone with Sulfamethoxazole?
MediHelp rates the interaction as moderate. Metolazone and Sulfamethoxazole 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 thiazide-type diuretics and sulfamethoxazole-trimethoprim can lower serum sodium, and the combination may increase hyponatremia risk, especially in older adults. Hyperkalemia from trimethoprim may partly offset diuretic potassium loss.
How serious is the interaction between Metolazone and Sulfamethoxazole?
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 and potassium within the first week of combined therapy, particularly in elderly patients, and stop or change therapy if significant hyponatremia 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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