Chlorothiazide and Furosemide interaction
Chlorothiazide and Furosemide: both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Chlorothiazide (DIURIL) label · effective 2021-11-01
Thiazides may add to or potentiate the action of other antihypertensive drugs.
Lithium generally should not be given with diuretics (see PRECAUTIONS , Drug Interactions ).
Other Antihypertensive Drugs - additive effect or potentiation.
Diuretic agents reduce the renal clearance of lithium and add a high risk of lithium toxicity.
Non-steroidal Anti-inflammatory Drugs (NSAIDs) Including Selective Cyclooxygenase-2 (COX-2) Inhibitors - In some patients, the administration of a non-steroidal anti-inflammatory agent including a selective COX-2 inhibitor can reduce the diuretic, natriuretic, and antihypertensive effects of loop, potassium-sparing and thiazide diuretics.
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.