Spironolactone and Losartan: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Spironolactone
Losartan
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
An increased risk of hyperkalemia, an increased risk of hypotension and an increased risk of worsening of renal function
Interaction Deep Dive
Concomitant use of spironolactone and angiotensin receptor blockers (ARBs) it may lead to severe hyperkalemia12. Excessive diuresis may cause symptomatic dehydration, hypotension and worsening renal function may also occur. Monitor serum potassium within 1 week of initiation or titration of spironolactone and regularly thereafter. More frequent monitoring may be needed when spironolactone is given with ARBs. If hyperkalemia occurs, reduce the dose or discontinue spironolactone and treat hyperkalemia 2. The onset of diuresis with spironolactone occurs promptly and, due to prolonged effect of the spironolactone component, persists for two to three days after spironolactone is discontinued 1.
Why it happens (mechanism)
Reduced renal clearance
Common questions
Can I take Spironolactone and Losartan together?
An increased risk of hyperkalemia, an increased risk of hypotension and an increased risk of worsening of renal function Always confirm with your pharmacist or prescriber before making any change.
How serious is the Spironolactone and Losartan interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Spironolactone or Losartan need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (2)
- Product Information: Aldactazide® oral tablets, spironolactone hydrochlorothiazide oral tablets. Pfizer Labs (per FDA), New York, NY, 2025.
- Product Information: ALDACTONE® oral tablets, spironolactone oral tablets. Pfizer Labs (per FDA), New York, New York, 2025. DailyMed
Keep reading about Spironolactone
Keep reading about Losartan
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist