Carbinoxamine and Buprenorphine: 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
Carbinoxamine
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 an opioid used for pain or for treating opioid use disorder, and carbinoxamine is a sedating antihistamine. Taken together, their calming effects can stack up. That can mean too much drowsiness, slowed breathing, and deep sedation. Because both can slow the gut and bladder, you may also notice severe constipation or trouble urinating, which in rare cases can become serious.
The good news is that your care team can manage this. Please don't stop either medicine on your own. Talk with your pharmacist or doctor so they can review your doses and watch you more closely if you need both.
Effect: Additive CNS and respiratory depression, plus additive anticholinergic/opioid effects on GI and bladder motility (constipation, urinary retention, potential paralytic ileus).
Mechanism: Pharmacodynamic additive CNS depression; combined reduction in gastric motility. Not a CYP-mediated PK interaction; neither agent is relevant here as an activation-dependent prodrug.
- Direction: Increased sedative and respiratory-depressant effect.
- Severity/evidence: Major; probable substantiation.
- Management: Use lowest effective doses; monitor sedation, respiratory rate, bowel and bladder function. Consider non-sedating alternatives for allergy symptoms. Do not withhold buprenorphine-based MAT solely due to this interaction.
What happens
An increased risk of respiratory and CNS depression and an increased risk of paralytic ileus
Interaction Deep Dive
Using buprenorphine together with an anticholinergic CNS depressant can produce additive CNS depression and heighten the likelihood of respiratory depression, deep sedation, coma, and death, and it may additionally provoke urinary retention and/or severe constipation, potentially progressing to paralytic ileus. Rather than using them together, discontinuing benzodiazepines or other CNS depressants is the preferred approach. For certain patients, it may be suitable to observe them in a higher level of care or to implement a taper. For others, slowly tapering the patient off a prescribed benzodiazepine or other CNS depressant, or reducing to the smallest effective dose, may be suitable. When combined use cannot be avoided, watch for urinary retention, severe constipation, sedation, and respiratory depression, and weigh alternative therapies for managing anxiety or insomnia1. A Swedish epidemiological study found that patients on methadone- or buprenorphine-based medication-assisted treatment (MAT) together with benzodiazepines or other CNS depressants face a greater risk of death. An analysis of pooled nationwide death certificate records spanning 2010 to 2014 showed that most overdose deaths involving buprenorphine and methadone also involved concurrent CNS depressant use. Whether the risk of overdose death associated with concomitant CNS depressant drugs varied between buprenorphine and methadone remains unknown 2.
Why it happens (mechanism)
Additive CNS depression; additive effects on gastric motility
How to manage this interaction
If you are prescribed both, keep taking them as directed unless your prescriber tells you otherwise. Your care team can manage this by tailoring your regimen and watching you more closely.
- Your doses may be adjusted and individualized, often aiming for the lowest effective dose of the sedating antihistamine.
- Your team may consider a non-sedating alternative for allergy symptoms.
- Watch for excessive drowsiness, slow or shallow breathing, confusion, severe constipation, or trouble urinating, and report these promptly.
Do not stop buprenorphine on your own. Ask your pharmacist or prescriber before adding any other sedating medicine, alcohol, or sleep aid.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) A Swedish epidemiological study reported that patients receiving methadone- or buprenorphine-based medication-assisted treatment (MAT) together with benzodiazepines or other CNS depressants (for example, drugs used to treat insomnia) have an increased risk of death. From July 1, 2005 to December 31, 2012, the risk of fatal overdose, non-overdose related mortality, and all-cause mortality during periods of prescribed CNS depressants compared with periods without CNS depressant therapy was analyzed in MAT prescribed 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 MAT and benzodiazepine treatment; however, the data were not considered statistically significant. Although the results showed a raised risk of fatal overdose, non-overdose mortality, and all-cause mortality during periods of coadministration of MAT and non-benzodiazepines, only the data for fatal overdose and all-cause mortality were considered statistically significant; HR 2.34 (95% CI, 1.37 to 3.99) and HR 1.33 (95% CI, 1.12 to 2.45), respectively. A comparison between the benzodiazepine cohort and non-benzodiazepine cohort was not performed because the authors did not adjust for the indication of use for the drugs 2.
b) According to a study of aggregate nationwide death certificate data from 2010 to 2014, 3495 drug overdose deaths were reported in 2014. Methadone and other CNS depressants were frequently identified as contributors in those deaths. Concurrent alprazolam use was reported in 18.1% of cases, followed by oxycodone (10.1%), cocaine (9.6%), heroin (9%), and diazepam (6.6%). The FDA reported 322 drug overdose deaths in 2014 involving buprenorphine. Of 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 number of methadone-involved deaths was 10 times the number of buprenorphine-involved deaths, although confounding factors and differences in drug utilization were not accounted for. Whether the risk of overdose death with concomitant CNS depressant drugs differed between buprenorphine and methadone is unknown 2.
Common questions
Can I take Carbinoxamine and Buprenorphine together?
Combining buprenorphine with carbinoxamine adds up their sedating effects and can slow breathing, cause deep sedation, and worsen constipation or urinary retention. Keep taking both as prescribed, but ask your care team about lower doses or a non-sedating allergy option and watch for excessive drowsiness or breathing changes. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Carbinoxamine and Buprenorphine 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 Carbinoxamine and Buprenorphine interaction managed?
If you are prescribed both, keep taking them as directed unless your prescriber tells you otherwise. Your care team can manage this by tailoring your regimen and watching you more closely. Your doses may be adjusted and individualized, often aiming for the lowest effective dose of the sedating antihistamine. Your team may consider a non-sedating alternative for allergy symptoms. Watch for excessiv… 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.
Questions for your pharmacist
- Does my dose of Carbinoxamine or Buprenorphine 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 (2)
- 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 Carbinoxamine
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