Can You Take Losartan and Potassium Together?
Losartan's FDA label directly advises against using potassium supplements without a doctor's guidance, due to the risk of high potassium levels.
See the full Losartan page and Potassium page for other reviewed interactions and reference information.
What the interaction means
Losartan's FDA prescribing information states in its patient counseling section: "Advise patients receiving Losartan potassium not to use potassium supplements or salt substitutes containing potassium without consulting their healthcare provider." The drug interactions section (7.1) states: "Coadministration of losartan with other drugs that raise serum potassium levels may result in hyperkalemia. Monitor serum potassium in such patients." The warnings section (5.4) adds: "Monitor serum potassium periodically and treat appropriately. Dosage reduction or discontinuation of Losartan potassium may be required." NIH's Office of Dietary Supplements independently corroborates this, naming losartan specifically: "angiotensin receptor blockers (ARBs) such as losartan (Cozaar)... reduce urinary potassium excretion, which can lead to hyperkalemia," recommending potassium status be monitored in people taking ARBs.
Why it may happen
As an ARB, losartan blocks angiotensin II receptors, which reduces aldosterone and causes the kidneys to retain more potassium. Adding a potassium supplement on top of this effect can raise blood potassium levels further.
Practical context
This is consultation/monitoring-oriented language rather than an outright 'avoid' directive -- similar in tenor to the existing Lisinopril + Potassium record (an ACE inhibitor working via a related but distinct mechanism, also rated 'monitor' on this site) and notably less absolute than the existing Potassium + Spironolactone record, which uses explicit 'avoid' language for a potassium-sparing diuretic.
What the sources say
Last reviewed 2026-08-24
Medical information disclaimer: this information is general and educational. It does not diagnose conditions, prescribe treatment, or determine whether a combination is safe for you personally. Follow your prescription label and ask a pharmacist or clinician before starting, stopping, or combining products. Full disclaimer.
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