Lisinopril and Potassium: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Potassium
Lisinopril
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.
Taking a potassium supplement with lisinopril can raise your potassium too high. Lisinopril is a blood pressure medicine that helps your body hold on to more potassium. When you add a potassium supplement on top of that, the level in your blood can climb, sometimes over a few days.
Too much potassium can affect your heartbeat, so this is worth watching. The good news is your care team can manage it easily with a simple blood test to check your level. Don't stop or change either medicine on your own. Just talk with your pharmacist or doctor, and let them know about any salt substitutes too, since many contain potassium.
Effect: Additive hyperkalemia risk when potassium supplements are combined with lisinopril.
Mechanism: Lisinopril (ACE inhibitor) reduces angiotensin II, lowering aldosterone and decreasing renal potassium excretion. Exogenous potassium compounds this, raising serum K+.
- Direction: Increased serum potassium (additive PD effect).
- Onset: Delayed; typically evident within 2 to 4 days, especially in renal impairment.
- Evidence: Established; case reports of severe hyperkalemia and arrhythmias.
- Management: Monitor serum potassium; higher vigilance in renal dysfunction and elderly. Potassium dose may need individualizing. Counsel on dietary potassium and potassium-containing salt substitutes.
What happens
Hyperkalemia
Interaction Deep Dive
As an angiotensin-converting enzyme (ACE) inhibitor, lisinopril can reduce aldosterone concentrations, an effect that may lead to the retention of potassium. Case reports have documented serious hyperkalemia and arrhythmias when potassium supplements were taken together with ACE inhibitor therapy624. Among patients who have renal dysfunction or who are taking potassium supplements, the rise in serum potassium typically becomes apparent within two to four days178.
Why it happens (mechanism)
Lowered aldosterone levels
How to manage this interaction
This combination is manageable with monitoring. Keep taking both exactly as prescribed unless your care team tells you otherwise.
- Your team will likely check your blood potassium level, especially in the first few days and if you have kidney problems or are older.
- Your potassium supplement dose may be adjusted and individualized by your care team.
- Watch out for salt substitutes and diet supplements, which often contain potassium, and mention them to your pharmacist.
- Report symptoms like muscle weakness, an irregular or slow heartbeat, or numbness and tingling.
Raise any questions with your pharmacist or prescriber.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
4 reports — tap to read
a) An 81-year-old woman with a history of congestive heart failure and acute myocardial infarction came to the hospital with chest discomfort 2. She had been regularly using diltiazem, furosemide, digoxin, isosorbide mononitrate, and aspirin, along with captopril 25 mg three times daily. She was also receiving potassium 1200 mg twice daily because of ongoing hypokalemia during a prior hospitalization. On examination and after serum electrolytes were measured, the patient displayed a slow atrial fibrillation, a heart rate of 36 beats per minute, and a serum potassium concentration of 8.2 mmol/L. Following treatment with calcium gluconate, dextrose, insulin, furosemide, and sodium polystyrene sulfonate, her serum potassium fell to 5.4 mmol/L and normal sinus rhythm was restored. The authors observed that life-threatening hyperkalemia can develop late during ACE inhibitor therapy, and they recommended monitoring of renal function and potassium.
b) A 59-year-old man was admitted for management of an acute worsening of congestive heart failure and hypertension 3. At admission his serum potassium was 4.3 mEq/L (4.3 mmol/L). Captopril 12.5 mg every eight hours was subsequently added to his existing regimen of furosemide and oral nitrates. Over the following days his serum potassium gradually rose to a level of 5.
c) A 64-year-old woman came to the emergency room with a 36-hour history of intermittent vomiting 4. She was being treated with lisinopril 10 mg daily and theophylline 600 mg daily. Over the previous six months she had lost 33.8 kg on a daily diet made up of a protein supplement containing 48 mmol potassium and an evening salad with a salt substitute providing 72 mmol potassium. She reported severe weakness, had a serum potassium concentration of 9.7 mmol/L, and demonstrated electrocardiographic changes consistent with hyperkalemia, including widening of the QRS complex. After intravenous treatment with calcium gluconate, insulin, dextrose, and sodium bicarbonate, her serum potassium returned to normal over the next 12 hours. The authors proposed that the patient developed life-threatening hyperkalemia because of lisinopril inhibition of aldosterone secretion together with a diet supplying more than 120 mmol potassium per day.
d) Two patients who developed hyperkalemia from the addition of potassium-containing salt substitutes have been reported. The first, a 67-year-old man taking atenolol 100 mg daily, furosemide 40 mg daily, aspirin 75 mg daily, and lisinopril 20 mg daily, presented with a three-day history of dizziness and vomiting. His serum potassium was 7.6 mmol/L, and treatment with insulin and dextrose was begun. An electrocardiogram revealed a pronounced sinus bradycardia, and the patient experienced a brief cardiac arrest. It was found that in the week before admission he had been adding 70 mmol of potassium daily to his diet in the form of a salt substitute, which was thought to be responsible for his hyperkalemia. The second patient, a 64-year-old man, was started on enalapril 2.5 mg twice daily for hypertension and had a serum potassium of 5 mmol/L. Four months later his potassium had risen to 7 mmol/L. The hyperkalemia was corrected with insulin and dextrose, and the enalapril was stopped. The patient reported that he had begun using a salt substitute, and further inquiry showed he was adding 133 mmol of potassium daily to his diet from the salt substitute. Enalapril was restarted, the salt substitute was discontinued, and two months later his potassium was 5.7 mmol/L 5.
Common questions
Can I take Lisinopril and Potassium together?
Combining a potassium supplement with lisinopril can push your potassium too high, which can affect your heart, so your care team should monitor your blood potassium and watch out for potassium-containing salt substitutes. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Lisinopril and Potassium interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How is the Lisinopril and Potassium interaction managed?
This combination is manageable with monitoring. Keep taking both exactly as prescribed unless your care team tells you otherwise. Your team will likely check your blood potassium level, especially in the first few days and if you have kidney problems or are older. Your potassium supplement dose may be adjusted and individualized by your care team. Watch out for salt substitutes and diet supplement… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "established". Well documented — supported by controlled studies or strong clinical data.
From our Q&A
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Questions for your pharmacist
- Does my dose of Lisinopril or Potassium 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 (8)
- Burnakis TG & Mioduch HJ: Combined therapy with captopril and potassium supplementation. A potential for hyperkalemia. Arch Intern Med 1984; 144:2371-2372. DOI
- Chan TYK & Critchley JAJH: Life-threatening hyperkalaemia in an elderly patient receiving captopril, furosemide (frusemide) and potassium supplements. Drug Safety 1992; 7:159-161. PubMed
- Burnakis TG: Captopril and increased serum potassium levels. JAMA 1984; 252:1682-1683. DOI
- Stoltz ML & Andrews CE: Severe hyperkalemia during very-low-calorie diets and angiotensin converting enzyme use. JAMA 1990; 264:2737-2738. DOI
- Ray KK, Dorman S, & Watson RDS: Severe hyperkalaemia due to the concomitant use of salt substitutes and ACE inhibitors in hypertension: a potentially life threatening interaction. J Hum Hypertens 1999; 13:717-720. PubMed
- Product Information: Zestril(R), lisinopril. AstraZeneca Pharmaceuticals LP, Wilmington, DE, 2003. DailyMed
- Cook B: Angiotensin converting enzyme inhibitors and diuretics (letter). Br Med J (Clin Res) 1987; 295:1351-1352. PubMed
- Textor SC, Bravo EL, Fouad FM, et al: Hyperkalemia in azotemic patients during angiotensin-converting enzyme inhibition and aldosterone reduction with captopril. Am J Med 1982; 73:719-725. PubMed
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