Labetalol and Isoflurane: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Isoflurane
Labetalol
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
Hypotension or decreased cardiac output
Interaction Deep Dive
The concurrent use of labetalol and inhalational anesthetics (halothane, enflurane, isoflurane) has been reported to have synergistic hypotensive effects423. Although this may be used as a means to reduce blood loss during surgery, the risks may outweigh the benefits for some patients, necessitating alternative anesthesia. Caution should be exercised when using these agents concurrently.
Why it happens (mechanism)
Additive hypotensive and cardiodepressive effects
Literature reports
1 report — tap to read
a) The combination use of labetalol and isoflurane has been used to induce deliberate hypotension to reduce bleeding in various types of surgery that require a clear operative field. Studies have shown that intravenous labetalol decreases the induction time of hypotension and the recovery time after anesthesia. It also decreases the isoflurane concentration in inspiratory gas needed to maintain deliberate hypotension 1. Patients who receive both labetalol and isoflurane during surgery show no impairment in neuropsychological function following hypotensive general anesthesia compared to normotensive general anesthesia 5.
Common questions
Can I take Labetalol and Isoflurane together?
Hypotension or decreased cardiac output Always confirm with your pharmacist or prescriber before making any change.
How serious is the Labetalol and Isoflurane 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 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 Labetalol or Isoflurane 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 (5)
- Toivonen J, Virtanen H, & Kaukinen S: Labetalol attenuates the negative effects of deliberate hypotension induced by isoflurane. Acta Anaesthesiol Scand 1992; 36:84-88. PubMed
- Hunter JM: Synergism between halothane and labetalol. Anaesthesia 1979; 34:257-259. PubMed
- Scott DB, Buckley FP, Littlewood DG, et al: Circulatory effects of labetalol during halothane anaesthesia. Anaesthesia 1978; 33:145-156. PubMed
- Toivonen J, Virtanen H, & Kaukinen S: Deliberate hypotension induced by labetalol with halothane, enflurane or isoflurane for middle-ear surgery. Acta Anaesthesiol Scand 1989; 33:283-289. PubMed
- Toivonen J, Kuikka P, & Kaukinen S: Effects of deliberate hypotension induced by labetalol with isoflurane on neuropsychological function. Acta Anaesthesiol Scand 1993; 37:7-11. PubMed
Keep reading about Isoflurane
Keep reading about Labetalol
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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