Common Medications Causing Hyperkalemia and Hypokalemia
Drugs That Cause Hyperkalemia
The most common medications causing hyperkalemia are renin-angiotensin-aldosterone system (RAAS) inhibitors, potassium-sparing diuretics, and NSAIDs—with reduced renal potassium excretion being the predominant mechanism. 1
RAAS Inhibitors (Most Important Class)
- ACE inhibitors (e.g., enalapril, lisinopril, ramipril, captopril) 1, 2
- Angiotensin receptor blockers (ARBs) (e.g., losartan, valsartan, candesartan, irbesartan) 1, 2
- Mineralocorticoid receptor antagonists (MRAs) (e.g., spironolactone, eplerenone) 1, 2
- Direct renin inhibitors (aliskiren) 1, 2
- Sacubitril/valsartan 1
These agents cause hyperkalemia by inhibiting the RAAS, which represents the most important mechanism by which drugs induce hyperkalemia in clinical practice. 1, 3 The incidence increases to 5-10% when dual RAAS therapy is used in patients with heart failure or chronic kidney disease. 1
Potassium-Sparing Diuretics
These agents block the kaliuretic effects of aldosterone and should be avoided with potassium supplements or in patients with significant renal dysfunction (GFR <45 mL/min). 2, 4
Other Common Hyperkalemia-Causing Drugs
- Beta-blockers (all types, including atenolol, metoprolol, carvedilol) 1, 3
- NSAIDs (all non-steroidal anti-inflammatory drugs) 1, 5
- Calcineurin inhibitors (cyclosporine, tacrolimus) 1, 3
- Trimethoprim-sulfamethoxazole 1, 3
- Heparin and derivatives 1, 3
- Pentamidine 1, 3
- Digitalis 1
- Penicillin G (high doses) 1
- Mannitol 1, 3
Critical Risk Amplifiers
Drug-induced hyperkalemia is particularly dangerous when multiple risk factors coexist: renal insufficiency, diabetes mellitus, advanced age, and concurrent use of multiple hyperkalemia-inducing medications. 1, 6 In one study, underlying disease states compromised potassium regulation in more than 80% of drug-related hyperkalemic episodes. 7
Drugs That Cause Hypokalemia
Thiazide and loop diuretics are by far the most common causes of drug-induced hypokalemia, with chlorthalidone carrying higher risk than hydrochlorothiazide at equivalent doses. 8
Loop Diuretics (Highest Risk)
Loop diuretics are preferred in patients with moderate-to-severe CKD (GFR <30 mL/min) but carry significant hypokalemia risk. 2
Thiazide and Thiazide-Like Diuretics
- Hydrochlorothiazide (25-75 mg daily) 2, 4
- Chlorthalidone (12.5-50 mg daily) 2, 8
- Metolazone 4
- Indapamide 4
Chlorthalidone poses significantly higher risk than hydrochlorothiazide: In elderly patients, chlorthalidone increased the risk of hospitalization for hypokalemia 3-fold compared to hydrochlorothiazide (adjusted HR: 3.06; 95% CI: 2.04-4.58). 8 In the ALLHAT trial, 8.5% of chlorthalidone patients developed hypokalemia (<3.5 mEq/L) versus only 0.8% on lisinopril after 4 years. 8
Other Hypokalemia-Causing Drugs
- Beta-2 adrenergic agonists (e.g., albuterol/salbutamol) cause transcellular potassium shift 1, 5
- Theophylline derivatives lower serum potassium, particularly in overdose 5
- Insulin (when used therapeutically, causes intracellular potassium shift) 1
- High-dose penicillins (can cause renal potassium wasting) 1
Hypokalemia Severity and Monitoring
Up to 56% of individuals taking diuretics develop hypokalemia. 9 The risk is dose-dependent, with both thiazide and loop diuretics showing increasing hypokalemia rates at higher doses. 8 After 5 years in ALLHAT, 8% of chlorthalidone patients required potassium supplementation versus only 2% on lisinopril. 8
Key Clinical Pitfalls
Avoid combining potassium-sparing diuretics with ACE inhibitors or ARBs in patients with renal impairment (GFR <45 mL/min), as this dramatically increases hyperkalemia risk. 2, 4 Conversely, the concurrent use of ACE inhibitors with thiazide diuretics may partially offset hypokalemia risk through potassium retention. 8
Monitor electrolytes 1-2 weeks after initiating or changing doses of any RAAS inhibitor or diuretic, then at 3 months, and every 6 months thereafter. 1, 4 Inadequate monitoring is associated with higher hospitalization rates and increased mortality. 1
Drug-induced hyperkalemia is frequently iatrogenic and often involves multiple contributing medications plus underlying renal disease—systematically evaluate all potential causes rather than attributing hyperkalemia to renal failure alone. 1, 6