Medications That Cause Hyperkalemia
The most clinically important medications causing hyperkalemia are renin-angiotensin-aldosterone system inhibitors (RAASi), including ACE inhibitors, angiotensin receptor blockers (ARBs), mineralocorticoid receptor antagonists (MRAs like spironolactone and eplerenone), and direct renin inhibitors, along with potassium-sparing diuretics, NSAIDs, and trimethoprim-sulfamethoxazole. 1
Primary Medication Categories
RAAS Inhibitors (Most Common Cause)
The reduction in renal potassium excretion through RAAS inhibition represents the most important mechanism by which drugs cause hyperkalemia 2:
- ACE inhibitors (captopril, enalapril, lisinopril)
- Angiotensin receptor blockers (losartan, valsartan)
- Mineralocorticoid receptor antagonists (spironolactone, eplerenone) - particularly high risk 3, 1
- Angiotensin receptor-neprilysin inhibitors (sacubitril/valsartan) 1
- Direct renin inhibitors (aliskiren) 1
Critical monitoring point: Spironolactone and eplerenone can cause hyperkalemia and worsening renal function, which were uncommon in RCTs but occur more frequently in ordinary clinical practice, especially in the elderly 3. Both should only be used in patients with adequate renal function (creatinine <200 μmol/L or <2.5 mg/dL) and normal serum potassium (<5.2 mmol/L for spironolactone, <5.5 mmol/L for eplerenone) 4, 5.
Potassium-Sparing Diuretics
- Spironolactone
- Triamterene
- Amiloride
These may cause severe hyperkalemia, especially when combined with ACE inhibitors or ARBs 6, 1.
Other High-Risk Medications
Beta-blockers - Impair potassium excretion and can shift potassium extracellularly 1, 2
NSAIDs - Block prostaglandin-mediated potassium excretion; particularly dangerous when combined with RAASi 1, 2
Trimethoprim-sulfamethoxazole - Should be used with extreme caution in patients with reduced kidney function taking ACE inhibitors or ARBs due to increased hyperkalemia risk 7, 1
Calcineurin inhibitors (cyclosporine, tacrolimus) 1, 2
Heparin and derivatives - Suppress aldosterone synthesis 1, 2
Digitalis (digoxin) 1
Penicillin G (high-dose) 1
Medications Causing Transcellular Potassium Shift
These medications move potassium from intracellular to extracellular space 2:
- Mannitol 1
- Suxamethonium 2
- Certain calcium channel blockers 2
- Amino acids (aminocaproic acid, arginine, lysine) 1
High-Risk Drug Combinations
The combination of ACE inhibitor/ARB + MRA + trimethoprim is particularly dangerous and should be avoided unless followed closely in a specialist clinic 4. The 2019 AGS Beers Criteria specifically warns that concurrent use of three or more medications that increase serum potassium significantly elevates risk 7.
Risk Factors Amplifying Medication-Induced Hyperkalemia
Monitor more intensively when medications are combined with 8:
- Chronic kidney disease (GFR <45 mL/min/1.73 m²)
- Baseline serum potassium >4.5 mmol/L
- Diabetes mellitus
- Advanced age (>75 years)
- Multiple comorbidities
Monitoring Recommendations
For patients on RAASi therapy:
- Check potassium and renal function before initiating treatment
- Recheck at 1 and 4 weeks after starting or dose increases 3
- Then at 1,2,3, and 6 months after achieving maintenance dose
- Subsequently every 6 months 3
Action thresholds for spironolactone/eplerenone 3:
- Potassium 5.5-6.0 mmol/L: Halve the dose (e.g., 25 mg on alternate days) and monitor closely
- Potassium ≥6.0 mmol/L: Stop immediately and monitor blood chemistry closely; specific treatment may be needed
Critical Clinical Pitfall
Do not discontinue or down-titrate RAASi therapy as first-line management of hyperkalemia. Despite being common practice, RAASi withdrawal is associated with increased mortality, heart failure hospitalizations, and progression to end-stage kidney disease 9, 10. Instead, manage hyperkalemia through dietary modification, diuretics, or newer potassium binders (sodium zirconium cyclosilicate or patiromer) to enable continuation of life-saving RAASi therapy 9, 11.