Loratadine and Carbamazepine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Carbamazepine
Loratadine
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
Reduced CYP3A4 substrate exposure and reduced efficacy of CYP3A4 substrate
Interaction Deep Dive
Concomitant use of carBAMazepine (a strong CYP3A4 inducer) and a CYP3A4 substrate may result in reduced CYP3A4 substrate exposure. If coadministered, closely monitor CYP3A4 substrate levels and consider dose adjustments if needed12.
Why it happens (mechanism)
Induction of CYP3A4-mediated metabolism by carBAMazepine
Common questions
Can I take Loratadine and Carbamazepine together?
Reduced CYP3A4 substrate exposure and reduced efficacy of CYP3A4 substrate Always confirm with your pharmacist or prescriber before making any change.
How serious is the Loratadine and Carbamazepine 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 strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Loratadine or Carbamazepine 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: Tegretol(R)-XR oral extended-release tablets, carbamazepine oral extended-release tablets. Novartis Pharmaceuticals Corporation (per FDA), East Hanover, NJ, 2023. DailyMed
- Product Information: Tegretol(R) oral chewable tablets, oral tablets, oral suspension, carbamazepine oral chewable tablets, oral tablets, oral suspension. Novartis Pharmaceuticals Corporation (per FDA), East Hanover, NJ, 2023. DailyMed
Keep reading about Carbamazepine
Keep reading about Loratadine
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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