ModerateAntiplatelet agents (low dose) / NSAIDs (analgesic dose)×Angiotensin II receptor blockers (sartans)
Updated · Methodology
Mechanism
At high, anti-inflammatory doses aspirin suppresses renal prostaglandin synthesis. Together with losartan this lowers glomerular filtration, which in older or dehydrated patients can lead to acute kidney failure, and it can raise blood potassium (aspirin 100 mg and losartan SmPCs). Loss of vasodilating prostaglandins also weakens the blood-pressure-lowering effect of losartan. The US label for low-dose aspirin (FDA) describes the same kidney and blood pressure risks.
Symptoms
Blood pressure creeps up. If kidney function worsens, urine output falls, oedema appears, and creatinine and potassium rise on blood tests. The risk is higher in older patients, with dehydration, on diuretics, or with already reduced kidney function.
Management
The Spanish SmPCs describe the interaction mainly for high, anti-inflammatory aspirin doses (losartan and aspirin 100 mg SmPCs). With such doses, keep the patient well hydrated and check kidney function after starting the combination and periodically afterwards, with particular care in older patients (losartan SmPC). The FDA asks for periodic kidney checks even with low-dose aspirin when the patient is elderly, volume-depleted, on diuretics or has reduced kidney function (US aspirin label). Blood pressure is kept under close medical supervision (aspirin 100 mg SmPC), since losartan may work less well (losartan labels).
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Sources
- AHA: Use of Nonsteroidal Antiinflammatory Drugs: An Update for Clinicians. A Scientific Statement From the American Heart Association (2007)– Circulation 2007;115(12):1634–1642
- AGS: American Geriatrics Society Beers Criteria for Potentially Inappropriate Medication Use (2023)– By the 2023 American Geriatrics Society Beers Criteria Update Expert Panel. AGS Beers Criteria for Potentially Inappropriate Medication Use in Older Adults. J Am Geriatr Soc 2023;71(7):2052-2081.
- AEMPS: Ficha técnica: Losartan (nº registro 67729), sección 4.5 (2025)– AEMPS, CIMA, nº registro 67729, revisión 03/2025, sección 4.5
- AEMPS: Ficha técnica: Losartán (Cozaar 50 mg) (nº registro 60913), sección 4.5 (2025)– AEMPS, CIMA, nº registro 60913, revisión 03/2025, sección 4.5
- AEMPS: Ficha técnica: Ácido acetilsalicílico 100 mg (Adiro) (nº registro 62825), sección 4.5 (2026)– AEMPS, CIMA, nº registro 62825, revisión 07/2026, sección 4.5
- FDA: Cozaar (losartan potassium) prescribing information (2026)– FDA, DailyMed setid 9949448f-c3b9-44ee-94ed-c1aca8c90f39 (Organon LLC), revised 01/2026, sections 7.3
- FDA: Durlaza (aspirin) prescribing information (2015)– FDA, DailyMed setid 4c2a1403-3862-1efd-0a91-444989222b37 (New Haven Pharmaceuticals), revised 09/2015, sections 7