Furosemide and Metolazone interaction
Furosemide and Metolazone: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Metolazone label · effective 2026-01-15
Other Antihypertensive Drugs When metolazone tablets, USP, are used with other antihypertensive drugs, particular care must be taken to avoid excessive reduction of blood pressure, especially during initial therapy.
Furosemide Unusually large or prolonged losses of fluids and electrolytes may result when metolazone tablets, USP, are administered concomitantly to patients receiving furosemide (see PRECAUTIONS , Drug Interactions ).
WARNINGS Rapid Onset Hyponatremia And/Or Hypokalemia Rarely, the rapid onset of severe hyponatremia and/or hypokalemia has been reported following initial doses of thiazide and non-thiazide diuretics.
Serum potassium should be determined at regular and appropriate intervals, and dose reduction, potassium supplementation or addition of a potassium-sparing diuretic instituted whenever indicated.
Concomitant Therapy Lithium In general, diuretics should not be given concomitantly with lithium because they reduce its renal clearance and add a high risk of lithium toxicity.
From the Furosemide label · effective 2026-05-13
Monitor for changes in blood pressure and adjust the dose of other antihypertensive drugs if needed.
Monitor diuretic effects of furosemide and adjust the dose of furosemide if needed.
Patients receiving both indomethacin and furosemide should be observed closely to determine if the desired diuretic and/or antihypertensive effect of furosemide is achieved.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.