MajorPotassium-sparing diuretics (mineralocorticoid receptor antagonists)×Angiotensin II receptor blocker (ARB)
Updated · Methodology
Mechanism
Additive hyperkalaemia. Both drugs retain potassium: spironolactone directly blocks aldosterone receptors; telmisartan (ARB) reduces aldosterone synthesis.
Symptoms
Muscle weakness, paraesthesia, slowed pulse, arrhythmias. ECG: peaked T waves, widened QRS. Severe cases progress to cardiac arrest.
Management
The telmisartan SmPC (EMA) lists potassium-sparing diuretics, spironolactone included, under combinations that are not recommended. If the combination is needed, check serum potassium often. It is most often used in heart failure with reduced ejection fraction, where a mineralocorticoid receptor antagonist is part of core therapy (ESC 2021). Per the spironolactone SmPC, check potassium and creatinine within the first week after starting or increasing the dose, then monthly for 3 months, quarterly until the end of the first year and every 6 months after that. Stop spironolactone temporarily or permanently if potassium exceeds 5 mmol/L or creatinine exceeds 4 mg/dL (354 µmol/L). Do not give potassium supplements when potassium is above 3.5 mmol/L.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- ESC: ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure (2021)– McDonagh TA et al. Eur Heart J 2021;42:3599-3726
- EMA: Ficha técnica (SmPC EMA) de Micardis 40 mg comprimidos (telmisartán) (2026)– EMA SmPC vía AEMPS CIMA, nregistro 98090002 (EU/1/98/090), secciones 4.4, 4.5
- AEMPS: Ficha técnica de Aldactone 25 mg comprimidos (espironolactona) (2025)– AEMPS CIMA, nregistro 39059, secciones 4.4, 4.5
- FDA: Aldactone (spironolactone) tablets prescribing information (2025)– FDA label, DailyMed setid 0fed2822-3a03-4b64-9857-c682fcd462bc, sections 5.1, 7.1