Buprenorphine and Levocetirizine: 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
Buprenorphine
Levocetirizine
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 can make you sleepy. Buprenorphine is a strong opioid used for pain or opioid dependence, and it slows down the brain and breathing. Levocetirizine (Xyzal) is an allergy medicine, and even though many people think of it as non-drowsy, it can still cause some drowsiness in certain people.
When you take them together, those sleepy effects can add up. You might feel more tired, less alert, or slower to react, which matters for driving or focusing. The good news is your care team can manage this by watching how you feel and adjusting things if needed. Talk with your pharmacist or doctor before changing anything.
Mechanism: additive CNS depression. Buprenorphine, a partial mu-opioid agonist, produces sedation and respiratory depression; levocetirizine, though relatively non-sedating, can contribute to CNS depression. Neither is a prodrug here, so this is a pharmacodynamic (not pharmacokinetic) additive effect.
- Direction: increased sedation/psychomotor impairment.
- Severity/evidence: rated major, but substantiation is theoretical.
- Onset: unspecified.
Management: Manufacturer labeling advises avoiding concurrent use. If co-prescribed, counsel on additive sedation, avoid driving/hazardous tasks until effects known, and monitor for excessive somnolence or respiratory depression. Doses may need to be individualized by the care team.
What happens
Increased risk of CNS depression
Interaction Deep Dive
Concurrent administration of levocetirizine alongside CNS depressants should be avoided, since combining them may produce a further decrease in alertness together with further impairment of CNS performance1.
Why it happens (mechanism)
Additive CNS depression
How to manage this interaction
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. Because the two can add to each other's sedating effects, here is what typically helps:
- Your care team may monitor you more closely for excess drowsiness or slowed breathing.
- They may adjust or individualize doses, or consider a different allergy option if drowsiness is a problem.
- Avoid driving or hazardous activities until you know how the combination affects you.
- Limit alcohol and other sedating substances.
Raise any unusual sleepiness, confusion, or trouble breathing with your pharmacist or doctor promptly.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Buprenorphine and Levocetirizine together?
Taking buprenorphine and levocetirizine together can add up to more drowsiness and slower reactions, so avoid driving until you know how you feel and check with your pharmacist or doctor before making changes. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Buprenorphine and Levocetirizine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Buprenorphine and Levocetirizine interaction managed?
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. Because the two can add to each other's sedating effects, here is what typically helps: Your care team may monitor you more closely for excess drowsiness or slowed breathing. They may adjust or individualize doses, or consider a different allergy option if drowsiness is a problem. Avoid driving or hazardous activi… 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.
Questions for your pharmacist
- Does my dose of Buprenorphine or Levocetirizine 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 a safer alternative to one of these medications for me?
References (1)
- Product Information: Levocetirizine dihydrochloride oral tablets, levocetirizine dihydrochloride oral tablets. Apotex Corp (per DailyMed), Weston, FL, 2020. DailyMed
Keep reading about Buprenorphine
Keep reading about Levocetirizine
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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