Hydralazine and Furosemide: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Furosemide
Hydralazine
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.
What happens
An enhanced diuretic response to furosemide
Interaction Deep Dive
Concomitant hydrALAZINE and furosemide therapy has been reported to result in decreases in the furosemide half-life associated with increases in the plasma clearance. Furosemide plasma concentrations decreased despite unchanged endogenous creatinine clearance, indicating that the increased furosemide clearance was due to an increase in renal blood flow caused by hydrALAZINE1.
Why it happens (mechanism)
Increased furosemide renal clearance
Literature reports
1 report — tap to read
a) Twenty-five hospitalized patients with congestive heart failure (CHF) were divided into two groups, depending on the severity of their disease. Group 1 consisted of ten patients with moderate CHF whose physical activity was not restricted. Group 2 was made up of 15 patients with advanced CHF whose physical activity was greatly restricted. All patients were receiving conventional treatment for CHF, had been hospitalized for at least a week, and had been taking furosemide daily for at least four weeks. Both groups 1 and 2 received furosemide 40 mg as an intravenous bolus to determine the furosemide pharmacokinetics in patients with CHF. Eight patients from group 2 then received hydrALAZINE 0.2 mg/kg intravenously 30 minutes prior to a furosemide bolus. The elimination half-life was prolonged and the elimination rate constant and plasma clearance were smaller in group 2 (advanced CHF) than in group 1 (moderate CHF). In the group 2 patients who received both furosemide and hydrALAZINE, the furosemide half-life decreased from 96 minutes to 81 minutes, plasma clearance increased from 72.6 mL/min to 88.1 mL/min, and renal clearance rose from 45.4 mL/min to 60.9 mL/min. Creatinine clearance was not altered. These results indicated that hydrALAZINE increased renal blood flow, causing an increase in the diuretic effect of furosemide 1.
Common questions
Can I take Hydralazine and Furosemide together?
An enhanced diuretic response to furosemide Always confirm with your pharmacist or prescriber before making any change.
How serious is the Hydralazine and Furosemide interaction?
It is rated minor. Usually limited clinical impact.
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 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 Hydralazine or Furosemide 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 (1)
- Nomura A, Yasuda H, Katoh K, et al: Hydralazine and furosemide kinetics. Clin Pharmacol Ther 1982; 32:303-306. DOI
Keep reading about Furosemide
Keep reading about Hydralazine
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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