Phenobarbital and Cariprazine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 16, 2026 · Source data updated Jul 16, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Phenobarbital
Cariprazine
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.
Phenobarbital can speed up how your body handles cariprazine (Vraylar). Phenobarbital revs up a liver enzyme called CYP3A4, and that same enzyme both creates and removes cariprazine's active forms. Because of this, the amount of active medicine in your body could shift, and honestly the exact net result hasn't been well studied.
The concern is that your cariprazine may not work as reliably when these are taken together, which is why this combination usually isn't recommended. Please don't stop or change either medicine on your own. Talk with your pharmacist or doctor. Your care team can watch how you're doing and adjust things to keep your treatment working well.
Interaction: Phenobarbital is a strong CYP3A4 inducer; cariprazine is a CYP3A4 substrate whose active metabolites (desmethyl- and didesmethyl-cariprazine) are both formed and cleared by CYP3A4.
- Direction/magnitude: Induction is expected to alter cariprazine and active-metabolite exposure, but because CYP3A4 governs both formation and elimination, the net PK effect is unpredictable and has not been formally studied.
- Evidence: Theoretical; onset unspecified.
- Management: Coadministration is not recommended. If unavoidable, monitor closely for loss of antipsychotic efficacy or altered response; dosing should be individualized by the care team.
What happens
Effects on the cariprazine exposure has not been evaluated and the net effect is unclear
Interaction Deep Dive
Using cariprazine (which is metabolized by CYP3A4) together with a CYP3A4 inducer is not advised. The formation as well as the clearance of cariprazine's active metabolites depends on CYP3A4. How CYP3A4 inducers influence cariprazine exposure has not been studied, so the overall outcome remains uncertain1.
Why it happens (mechanism)
Induction of CYP3A4-mediated metabolism of cariprazine
How to manage this interaction
What your care team may do:
- Because this combination generally isn't recommended, your prescriber may consider whether an alternative medication is a better fit.
- If both are needed, your team may monitor you more closely for changes in how well your cariprazine is working.
- Any dose changes may need to be adjusted and individualized by your care team.
What you should do:
- Keep taking both exactly as prescribed unless told otherwise.
- Tell your pharmacist or doctor about all your medicines, and report any return or worsening of symptoms.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Phenobarbital and Cariprazine together?
Phenobarbital may change how well cariprazine works because it speeds up the enzyme that both makes and clears cariprazine's active forms, and this combination generally isn't recommended. Talk with your care team so they can adjust or monitor your treatment. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Phenobarbital and Cariprazine 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 Phenobarbital and Cariprazine interaction managed?
What your care team may do: Because this combination generally isn't recommended, your prescriber may consider whether an alternative medication is a better fit. If both are needed, your team may monitor you more closely for changes in how well your cariprazine is working. Any dose changes may need to be adjusted and individualized by your care team. What you should do: Keep taking both exactly as… 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 Phenobarbital or Cariprazine 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: VRAYLAR(R) oral capsules, cariprazine oral capsules. AbbVie Inc. (per FDA), North Chicago, IL, 2024. DailyMed
Keep reading about Phenobarbital
Keep reading about Cariprazine
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