Bendroflumethiazide and Lisinopril: 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
Bendroflumethiazide
No brand names on recordLisinopril
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.
Bendroflumethiazide is a water pill (diuretic) and lisinopril is a blood pressure medicine. Both lower your blood pressure, so taking them together can lower it more than either alone. This matters most right when lisinopril is first started, because the water pill has already reduced the fluid and salt in your body.
The main thing to watch for is feeling dizzy or lightheaded, especially when you stand up quickly. The good news is this effect is usually temporary and settles down. Your care team can manage it easily by adjusting doses and checking on you. Keep taking both as prescribed, and let your doctor or pharmacist know if you feel faint.
Effect: Additive antihypertensive response, with risk of first-dose hypotension when the ACE inhibitor (lisinopril) is initiated in a patient already on the thiazide diuretic (bendroflumethiazide).
- Mechanism: Vasodilation from ACE inhibition combined with diuretic-induced intravascular volume/sodium depletion.
- Onset: Rapid; typically transient postural hypotension.
- Evidence: Theoretical; more commonly reported with loop diuretics but applies to thiazides in volume-depleted patients. Neither drug is a prodrug.
- Management: Before ACE inhibitor initiation, consider reducing/holding the diuretic or liberalizing salt intake; otherwise start lisinopril at a low dose. Monitor BP, orthostatics, renal function, and electrolytes.
What happens
Reduction of blood pressure
Interaction Deep Dive
When an ACE inhibitor is started in patients already receiving diuretics, blood pressure may fall to an excessive degree3. There have been reports of serious postural hypotension following the addition of ACE inhibitors to existing diuretic regimens. This reaction has been noted more frequently with loop diuretics, yet hypotension after the first dose occurs commonly in individuals who are sodium depleted or hypovolemic as a result of diuretic use or restricted sodium intake. In most cases, this drop in blood pressure is temporary6271. The likelihood of hypotensive effects can be lessened by reducing or stopping the diuretic, or by raising salt intake, prior to beginning ACE inhibitor treatment. When such steps cannot be taken, the initial dose of the ACE inhibitor should be lowered3.
Why it happens (mechanism)
Vasodilation and relative intravascular volume depletion
How to manage this interaction
This combination is used intentionally and can be managed well by your care team. The extra caution applies mainly when lisinopril is first started or increased.
- Keep taking both medicines exactly as prescribed unless your doctor tells you otherwise.
- Your team may lower or briefly pause the water pill, or adjust your salt intake, before starting or raising lisinopril.
- They may also start lisinopril at a lower dose and monitor your blood pressure more closely.
- Stand up slowly, and tell your pharmacist or doctor if you feel dizzy, lightheaded, or faint.
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) evaluating the combined use of hydrochlorothiazide and enalapril in older patients (62 to 84 years) found that the pharmacokinetics of enalapril remained relatively unchanged by hydrochlorothiazide, though there was a significant rise in AUC (0 to 24 hours) along with a significant decrease in the renal clearance of enalaprilat 4.
b) Concurrent use of perindopril and hydrochlorothiazide has been associated with a slight decrease in peak serum concentrations of perindoprilat, as well as a reduction in the proportion of the perindopril dose excreted as perindoprilat in the urine 5.
Common questions
Can I take Bendroflumethiazide and Lisinopril together?
Starting lisinopril while on the diuretic bendroflumethiazide can drop your blood pressure too much at first, causing dizziness, but this is usually temporary and your care team can manage it with dose adjustments and monitoring. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Bendroflumethiazide and Lisinopril 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 Bendroflumethiazide and Lisinopril interaction managed?
This combination is used intentionally and can be managed well by your care team. The extra caution applies mainly when lisinopril is first started or increased. Keep taking both medicines exactly as prescribed unless your doctor tells you otherwise. Your team may lower or briefly pause the water pill, or adjust your salt intake, before starting or raising lisinopril. They may also start lisinopri… 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 Bendroflumethiazide or Lisinopril 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 Bendroflumethiazide
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