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Can you take Prinivil®/Zestril® with Cozaar®?

Evidence-based interaction check between Prinivil®/Zestril® and Cozaar®

MajorEditorially reviewed · last updated April 15, 2025

High risk — avoid this combination unless there is no good alternative.

Hyperkalemia, symptomatic hypotension (light-headedness, fainting on standing), and acute kidney injury. The ONTARGET trial found combining the two offered no cardiovascular benefit over either drug alone but caused significantly more adverse renal events.

Why this happens (mechanism)

Lisinopril (an ACE inhibitor) and losartan (an ARB) both block the renin-angiotensin system, just at different steps. Doubling up doesn't double the blood-pressure benefit but does double the side-effect load — high potassium, low blood pressure on standing, and worsening kidney function.

What to monitor

  • Serum potassium and creatinine within 1-2 weeks of starting both
  • Blood pressure (sitting AND standing) at every visit
  • Symptoms of dizziness, fainting, muscle weakness (signs of hyperkalemia)

Dose adjustment

The combination is generally not recommended — choose either the ACE inhibitor or the ARB, not both. If a clinician has deliberately layered them (rare cases of resistant proteinuria), labs need monitoring at minimum every 1-2 weeks initially.

Safer alternatives to consider

Amlodipine (calcium channel blocker)

Add-on antihypertensive that doesn't stack with the renin-angiotensin block.

Hydrochlorothiazide (thiazide diuretic)

Standard add-on with complementary, not overlapping, mechanism.

Metoprolol (beta blocker)

Different class entirely; useful when heart rate also needs control.

Always discuss alternatives with your prescriber before making any change. The right choice depends on your other medications, conditions, and what is working for you today.

Evidence and sources

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Check another pair

3 interactions found

Major

Fatal hyperkalemia

Major

Dual RAAS blockade increases kidney failure and hyperkalemia, avoid combining

Major

ACE inhibitors reduce aldosterone, decreasing renal potassium excretion. Adding potassium supplementation creates serious hyperkalemia risk, potentially fatal cardiac arrhythmia. Potassium supplementation with ACE inhibitors requires physician monitoring and regular serum potassium testing.

View Prinivil®/Zestril® View Cozaar®

What this means

This summary is based on published interaction data from FDA prescribing information and clinical literature. It does not account for individual health factors, dosages, or other medications you may be taking. Always consult a qualified healthcare provider before making changes to your medication regimen.

Frequently Asked Questions

Is it safe to take Prinivil®/Zestril® with Cozaar®?

High risk — avoid this combination unless there is no good alternative. Hyperkalemia, symptomatic hypotension (light-headedness, fainting on standing), and acute kidney injury. The ONTARGET trial found combining the two offered no cardiovascular benefit over either drug alone but caused significantly more adverse renal events. Always discuss your full medication list with your prescriber.

What happens if you take Prinivil®/Zestril® and Cozaar® together?

Lisinopril (an ACE inhibitor) and losartan (an ARB) both block the renin-angiotensin system, just at different steps. Doubling up doesn't double the blood-pressure benefit but does double the side-effect load — high potassium, low blood pressure on standing, and worsening kidney function.

What should I monitor if I take both?

Serum potassium and creatinine within 1-2 weeks of starting both. Blood pressure (sitting AND standing) at every visit. Symptoms of dizziness, fainting, muscle weakness (signs of hyperkalemia).