Lisinopril and Hydrochlorothiazide: 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
Hydrochlorothiazide
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 lower your blood pressure, just in different ways. Hydrochlorothiazide is a water pill that removes extra fluid and salt, and lisinopril relaxes your blood vessels. When lisinopril is first added on top of a water pill, your blood pressure can drop more than expected, especially with that first dose.
You might feel dizzy or lightheaded, particularly when you stand up quickly. This is usually temporary and settles as your body adjusts. The good news is your care team knows about this and can manage it easily, often by adjusting your starting dose or checking on you a bit more closely. If you feel dizzy, sit or lie down and let them know.
Effect: Additive antihypertensive effect. Adding an ACE inhibitor (lisinopril) to established thiazide diuretic therapy (hydrochlorothiazide) may cause excessive BP reduction, including first-dose and postural hypotension.
- Mechanism: Lisinopril-mediated vasodilation superimposed on diuretic-induced volume/sodium depletion (PD interaction, not CYP-based). Neither agent is a relevant prodrug concern here.
- Onset: Rapid (first-dose).
- Evidence: Theoretical/pharmacologic; hypotension typically transient.
- Management: Consider reducing or holding the diuretic, or liberalizing sodium, before initiation; if not feasible, use a low ACE inhibitor starting dose. Monitor BP and orthostatic vitals early in therapy.
What happens
Reduction of blood pressure
Interaction Deep Dive
Adding an ACE inhibitor to the regimen of a patient already receiving diuretics can lead to an overly pronounced drop in blood pressure3. Cases of severe postural hypotension have been documented when ACE inhibitors are combined with diuretic treatment. While this effect is seen more frequently with loop diuretics, first dose hypotension occurs commonly in individuals who are sodium depleted or hypovolemic as a result of diuretics or dietary salt restriction. Typically, this hypotensive reaction is temporary6271. To limit the chance of hypotensive effects, the diuretic may be reduced or stopped, or salt intake may be raised, prior to beginning ACE inhibitor therapy. When such steps cannot be taken, lower the initial dose of the ACE inhibitor3.
Why it happens (mechanism)
Vasodilation and relative intravascular volume depletion
How to manage this interaction
These two are often prescribed together on purpose (the combo pill Zestoretic combines them), so the goal is safe use, not avoidance.
- Keep taking both as prescribed unless your prescriber tells you otherwise.
- Your care team may start the lisinopril at a low dose, adjust or briefly reduce your water pill, or advise on salt intake to soften the blood pressure drop.
- They may check your blood pressure more closely when you first start or change doses.
- Rise slowly from sitting or lying down for the first few days.
Tell your pharmacist or doctor if you feel dizzy, faint, or unusually weak, especially when standing.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) A randomized crossover study (N=19) examined the simultaneous use of hydrochlorothiazide and enalapril in older patients (62 to 84 years) and found that hydrochlorothiazide had relatively little effect on the pharmacokinetics of enalapril, although there was a significant rise in AUC (0 to 24 hours) along with a significant decrease in the renal clearance of enalaprilat 4.
b) A slight decrease in peak serum concentrations of perindoprilat, together with a reduction in the proportion of the perindopril dose eliminated as perindoprilat in the urine, has been noted when perindopril and hydrochlorothiazide are given together 5.
Common questions
Can I take Lisinopril and Hydrochlorothiazide together?
Starting lisinopril while on hydrochlorothiazide can cause a temporary, sometimes sharp drop in blood pressure, especially with the first dose; your care team can manage this with a low starting dose and closer monitoring. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Lisinopril and Hydrochlorothiazide interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How is the Lisinopril and Hydrochlorothiazide interaction managed?
These two are often prescribed together on purpose (the combo pill Zestoretic combines them), so the goal is safe use, not avoidance. Keep taking both as prescribed unless your prescriber tells you otherwise. Your care team may start the lisinopril at a low dose, adjust or briefly reduce your water pill, or advise on salt intake to soften the blood pressure drop. They may check your blood pressure… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
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 Hydrochlorothiazide 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 anything you'd monitor while I'm on both?
References (7)
- Vlasses PH, Ferguson RK, & Chatterjee K: Captopril: clinical pharmacology and benefit-to-risk ratio in hypertension and congestive heart failure. Pharmacotherapy 1982; 2:1-17. PubMed
- Gluck Z, Beretta-Piccoli C, & Reubi FC: Long-term effects of captopril on renal function in hypertensive patients. Eur J Clin Pharmacol 1984; 26:315-323. PubMed
- Product Information: QBRELIS(TM) oral solution, lisinopril oral solution. Silvergate Pharmaceuticals (per manufacturer), Greenwood Village, CO, 2016. DailyMed
- Weisser K, Schloos J, Jakob S, et al: The influence of hydrochlorothiazide on the pharmacokinetics of enalapril in elderly patients. Eur J Clin Pharmacol 1992; 43:173-177. PubMed
- Todd PA & Fitton A: Perindopril: a review of its pharmacological properties and therapeutic use in cardiovascular disorders. Drugs 1991; 42:90-114.
- Atkinson AB, Brown JJ, Morton JJ, et al: Captopril in a hyponatremic hypertensive; need for caution initiating therapy (letter). Lancet 1979; 1:557-558.
- Pandhi P, Mondal S, Sharma BK, et al: Low dose captopril alone and in combination with hydrochlorothiazide in treatment of mild to moderate essential hypertension. Int J Clin Pharmacol Ther Toxicol 1986; 24:294-297.
Keep reading about Hydrochlorothiazide
Keep reading about Lisinopril
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