Buprenorphine and Cetirizine: 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
Cetirizine
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.
Buprenorphine is a strong opioid used for pain or opioid use disorder, and it can slow your breathing and make you drowsy. Cetirizine (Zyrtec) is an allergy medicine that can also cause some drowsiness in some people. Taken together, the sleepy, calming effects can add up.
For most people cetirizine causes fairly mild drowsiness, but because buprenorphine already affects breathing, it is worth being aware of extra sleepiness or slowed breathing. Please don't stop either medicine on your own. Your pharmacist or doctor can review both, help you watch for warning signs, and adjust things if needed. This is very manageable when your care team knows you take both.
Mechanism: additive CNS depression. Buprenorphine is a partial mu-opioid agonist with respiratory-depressant potential; cetirizine is a second-generation antihistamine with relatively low but non-zero sedative effect. Neither is a prodrug here, so this is a pharmacodynamic (not PK) interaction.
- Direction: increased sedation and risk of respiratory depression
- Severity/evidence: rated major, evidence probable (largely a class effect for CNS depressants + buprenorphine)
- Onset: unspecified
Management: use lowest effective doses, monitor for excessive sedation and respiratory depression, and counsel accordingly. Cetirizine's sedative burden is modest, but caution rises in elderly, hepatic/respiratory impairment, or with other depressants. Do not withhold MAT.
What happens
An increased risk of respiratory depression and CNS depression
Interaction Deep Dive
When buprenorphine is given together with a CNS depressant, the effects on the CNS may be additive, raising the likelihood of respiratory depression, deep sedation, coma, and death. Discontinuing the CNS depressant is favored over using the two agents together. Depending on the situation, it may be suitable to observe the patient at a higher level of care or to institute a taper. In other circumstances, slowly weaning a patient off a prescribed CNS depressant, or reducing it to the smallest effective dose, may be warranted. Should concurrent use be required, exercise caution in monitoring and management, and weigh alternative therapies for anxiety or insomnia2. A Swedish epidemiological study found that patients on methadone- or buprenorphine-based medication-assisted treatment (MAT) who also took benzodiazepines or other CNS depressants (for example, agents used for insomnia) faced a heightened risk of death. An analysis of pooled national death certificate data spanning 2010 to 2014 showed that most overdose deaths involving buprenorphine and methadone also involved concurrent CNS depressant use. Whether the risk of fatal overdose with concomitant CNS depressant drugs was different for buprenorphine versus methadone remains unknown 3.
Why it happens (mechanism)
Additive CNS depression
How to manage this interaction
The main goal is to keep both medicines working safely while watching for too much sedation.
- Keep taking both as prescribed unless your prescriber tells you otherwise. Do not stop buprenorphine on your own.
- Your care team may use the lowest effective dose of each and monitor you more closely.
- Watch for unusual drowsiness, confusion, or slow/shallow breathing, and get help right away if these occur.
- Tell your pharmacist about all sedating products, including other allergy or sleep aids.
- Ask whether a non-drowsy allergy alternative is a better fit for you.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) A Swedish epidemiological study found that patients on methadone- or buprenorphine-based medication-assisted treatment (MAT) who also took benzodiazepines or other CNS depressants (for example, medications for insomnia) faced a greater risk of death. From July 1, 2005 through December 31, 2012, investigators compared the risk of fatal overdose, non-overdose related mortality, and all-cause mortality during periods when CNS depressants were prescribed versus periods without such therapy, in MAT patients aged 18 to 50. The findings showed a raised risk of all-cause mortality (adjusted hazard ratio (HR) 1.44; 95% CI, 0.93 to 2.23) and non-overdose related mortality (HR 1.74; 95% CI 1.00 to 3.01) with combined MAT and benzodiazepine treatment; however, these data were not deemed statistically significant. Although the results indicated a heightened risk of fatal overdose, non-overdose mortality, and all-cause mortality during periods of coadministration of MAT and non-benzodiazepines, only the fatal overdose and all-cause mortality data reached statistical significance; HR 2.34 (95% CI, 1.37 to 3.99) and HR 1.33 (95% CI, 1.12 to 2.45), respectively. The authors did not perform a comparison between the benzodiazepine cohort and the non-benzodiazepine cohort because they did not adjust for the indication of use for the drugs 3.
b) A study drawing on aggregate nationwide death certificate data spanning 2010 to 2014 documented 3495 drug overdose deaths in 2014. Methadone together with other CNS depressants were commonly cited as contributors to those deaths. Concurrent ALPRAZolam use appeared in 18.1% of cases, followed by oxyCODONE (10.1%), cocaine (9.6%), heroin (9%), and diazePAM (6.6%). The FDA documented 322 drug overdose deaths in 2014 that involved buprenorphine. Among these 322 deaths, 32.9% involved ALPRAZolam, 17.4% involved clonazePAM, 11.2% involved diazePAM, 11.2% involved heroin, and 9.9% involved fentaNYL. The absolute count of methadone-involved deaths was 10 times that of buprenorphine-involved deaths, though confounding factors and differences in drug utilization were not taken into account. Whether the risk of overdose death with concurrent CNS depressant drugs differed between buprenorphine and methadone is unknown 3.
Common questions
Can I take Buprenorphine and Cetirizine together?
Buprenorphine plus cetirizine can add up to more drowsiness and, rarely, slowed breathing; keep taking both as prescribed but ask your pharmacist about the least-sedating allergy option and watch for excessive sleepiness. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Buprenorphine and Cetirizine 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 Cetirizine interaction managed?
The main goal is to keep both medicines working safely while watching for too much sedation. Keep taking both as prescribed unless your prescriber tells you otherwise. Do not stop buprenorphine on your own. Your care team may use the lowest effective dose of each and monitor you more closely. Watch for unusual drowsiness, confusion, or slow/shallow breathing, and get help right away if these occur… Management is individual — always follow your own care team's guidance.
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 Buprenorphine or Cetirizine 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 (3)
- Product Information: BRIXADI(TM) subcutaneous extended-release injection, buprenorphine subcutaneous extended-release injection. Braeburn Inc (per FDA), Plymouth Meeting, PA, 2023. DailyMed
- Product Information: SUBUTEX(R) sublingual tablets, buprenorphine sublingual tablets. Indivior Inc (per FDA), North Chesterfield, VA, 2021. DailyMed
- US Food and Drug Administration (FDA): Drug Safety Communications: FDA urges caution about withholding opioid addiction medications from patients taking benzodiazepines or CNS depressants: careful medication management can reduce risks. US Food and Drug Administration (FDA). Silver Spring, MD. 2017.
Keep reading about Buprenorphine
Keep reading about Cetirizine
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist