Hydralazine and Oxprenolol: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Hydralazine
Oxprenolol
No brand names on record
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 increased risk of oxprenolol adverse effects (bradycardia, fatigue, bronchospasm)
Interaction Deep Dive
HydrALAZINE increases the oral bioavailability of propranolol, metoprolol, and oxprenolol (high clearance and lipophilic beta blockers). This occurs more frequently with a fasting state and does NOT occur with sustained-released beta-blockers34.
Why it happens (mechanism)
Increased oxprenolol bioavailability
Literature reports
2 reports — tap to read
a) Concomitant propranolol and hydrALAZINE therapy has been reported to increase peak propranolol levels (144 to 240%), reduce time to peak propranolol levels (175 to 214%), and increase the area under the propranolol concentration-time curve (61% to 112%) 1. HydrALAZINE had no effect on the fraction of propranolol excreted in the urine as basic, acidic, and polar metabolites. These effects are believed to be a result of hydrALAZINE hemodynamic effects rather than an inhibition of propranolol metabolism.
b) Concomitant administration of hydrALAZINE and a sustained release propranolol product (Inderal LA(R)) resulted in no alteration in peak propranolol concentrations, time to peak, or the area under the propranolol concentration/time curve 2.
Common questions
Can I take Hydralazine and Oxprenolol together?
An increased risk of oxprenolol adverse effects (bradycardia, fatigue, bronchospasm) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Hydralazine and Oxprenolol interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
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 Hydralazine or Oxprenolol 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 (4)
- Schneck DW & Vary JE: Mechanism by which hydralazine increases propranolol bioavailability. Clin Pharmacol Ther 1984; 35:447-453. PubMed
- Byrne AJ, McNeil JJ, Harrison PM, et al: Stable oral availability of sustained release propranolol when co-administered with hydralazine or food: evidence implicating substrate delivery rate as a determinant of presystemic drug interactions. Br J Clin Pharmacol 1984; 17(suppl):45S-50S. PubMed
- Mantyla R, Mannisto P, Nykanen S, et al: Pharmacokinetic interactions of timolol with vasodilating drugs, food and phenobarbitone in healthy human volunteers. Eur J Clin Pharmacol 1983; 24:227-230. DOI
- Lindeberg S, Holm B, Lundborg P, et al: The effect of hydralazine on steady-state plasma concentrations of metoprolol in pregnant hypertensive women. Eur J Clin Pharmacol 1988; 35:131-135. PubMed
Keep reading about Hydralazine
Keep reading about Oxprenolol
These medications also interact with supplements
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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