Lisinopril and Triamterene: 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
Triamterene
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.
Both of these medicines can raise the potassium level in your blood. Triamterene is a "potassium-sparing" water pill, which means it helps your body hold on to potassium. Lisinopril, a blood pressure medicine, also nudges your body to keep more potassium. Taken together, they can push your potassium higher than either one alone.
Too much potassium can affect your heartbeat, so this is worth taking seriously. The good news is that this is very manageable. Keep taking both exactly as prescribed, and your care team can check your potassium with a simple blood test and adjust things if needed. Ask your pharmacist or doctor if you have questions.
Effect: Additive hyperkalemia. Lisinopril (ACE inhibitor) suppresses aldosterone, reducing renal potassium excretion; triamterene (potassium-sparing diuretic) independently blocks distal potassium loss. Combined use has raised serum potassium by roughly 1 to 1.5 mEq/L versus either agent alone, occasionally precipitating serious arrhythmias.
- Direction/magnitude: Increased serum K+ (PD interaction, not prodrug-related).
- Onset: Delayed. Evidence: Probable. Severity: Major.
- Monitoring: Baseline and periodic serum potassium and renal function; more frequent in CKD, diabetes, elderly, volume depletion, or concurrent K+ supplements/NSAIDs.
- Management: Doses individualized; consider closer monitoring or alternative diuretic if K+ rises.
What happens
Increased risk of hyperkalemia
Interaction Deep Dive
By reducing aldosterone concentrations, angiotensin-converting enzyme (ACE) inhibitors can promote the retention of potassium1. When a potassium-sparing diuretic (spironolactone, canrenoate potassium, aMILoride, triamterene) is taken together with an ACE inhibitor, serum potassium has been reported to rise by 1 to 1.5 mEq/L relative to either agent administered on its own23. On occasion, this elevation has led to serious arrhythmias and fatalities45.
Why it happens (mechanism)
Increased potassium retention secondary to lowered aldosterone levels
How to manage this interaction
This combination is used sometimes, but your care team will watch it closely because both drugs raise potassium.
- Keep taking both as prescribed unless your doctor tells you otherwise. Do not stop on your own.
- Expect blood tests to check potassium and kidney function, especially when starting or changing doses.
- Your dose may need to be adjusted and individualized by your care team, or an alternative may be chosen if potassium runs high.
- Ask before using potassium supplements, salt substitutes, or NSAIDs (like ibuprofen), which can add to the effect.
- Report muscle weakness, an irregular or slow heartbeat, or tingling to your prescriber.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) A study assessed the safety of combining an ACE inhibitor (captopril) with a thiazide/potassium-sparing diuretic in 332 hypertensive patients whose blood pressure had failed to normalize on the diuretics alone. Only a single case of hyperkalemia (6 mmol/liter) was observed, along with a very low rate of hypotension (1.6%) 6.
b) The impact of adding spironolactone to an ACE inhibitor and a loop diuretic was assessed in 214 patients with severe chronic congestive heart failure. Patients were randomized into one of five parallel treatment arms: placebo or spironolactone given once daily at 12.5 mg, 25 mg, 50 mg, or 75 mg over 12 weeks. Hypokalemia (serum potassium below 3.4 mmol/L) was seen in 10% of placebo-treated patients and in 0.5% of the spironolactone group. Hyperkalemia (serum potassium at or above 5.5 mmol/L) occurred in 5% of the placebo group, compared with 5%, 13%, 20%, and 24% in the 12.5-, 25-, 50-, and 75-mg spironolactone treatment groups, respectively. Factors predicting hyperkalemia included the use of ACE inhibitors other than captopril, the ACE inhibitor dose, and elevated baseline serum creatinine or potassium levels. The authors concluded that daily spironolactone doses of 12.5 mg to 25 mg given together with conventional therapy of ACE inhibitors, loop diuretics, and digitalis are relatively safe, provided serum potassium levels are monitored 7.
Common questions
Can I take Lisinopril and Triamterene together?
Triamterene and lisinopril together can push potassium too high, which can affect heart rhythm; keep taking both as prescribed and let your care team monitor your potassium and adjust as needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Lisinopril and Triamterene 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 Triamterene interaction managed?
This combination is used sometimes, but your care team will watch it closely because both drugs raise potassium. Keep taking both as prescribed unless your doctor tells you otherwise. Do not stop on your own. Expect blood tests to check potassium and kidney function, especially when starting or changing doses. Your dose may need to be adjusted and individualized by your care team, or an alternativ… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Lisinopril or Triamterene 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 (7)
- Product Information: Prinivil(R), lisinopril. Merck & Co. Inc. Whitehouse Station, NJ, 2003. DailyMed
- Armayor GM & Lopez LM: Lisinopril: a new angiotensin-converting enzyme inhibitor. Drug Intell Clin Pharm 1988; 22:365-372. PubMed
- Burnakis TG & Mioduch HJ: Combined therapy with captopril and potassium supplementation. A potential for hyperkalemia. Arch Intern Med 1984; 144:2371-2372. DOI
- Lakhani M: Complete heart block induced by hyperkalemia associated with treatment with a combination of captopril and spironolactone (letter). Br Med J 1986; 293:271.
- Johnston RT, de Bono DP, & Nyman CR: Preventable sudden death in patients receiving angiotensin converting enzyme inhibitors and loop/potassium sparing diuretic combinations. Int J Cardiol 1992; 34:213-215. PubMed
- Schohn DC, Spiesser R, Wehrlen M, et al: Aldactazine/captopril combination, safe and effective in mild to moderate systemic hypertension: report on a multicenter study of 967 patients. Am J Cardiol 1990; 65:4K-6K. PubMed
- Anon: Effectiveness of spironolactone added to an angiotensin-converting enzyme inhibitor and a loop diuretic for severe chronic congestive heart failure (The Randomized Aldactone Evaluation Study (RALES)). Am J Cardiol 1996; 78:902-907.
Keep reading about Triamterene
Keep reading about Lisinopril
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