Acetaminophen And Codeine and Levocetirizine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jun 30, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Acetaminophen And Codeine
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. The codeine in your pain medicine is an opioid, and it slows down your brain and breathing. Levocetirizine (Xyzal) is an allergy medicine that can also cause drowsiness in some people. When you take them together, those sleepy effects can add up. You might feel more tired, foggy, dizzy, or slow to react.
This is a caution based on how these drugs work, not on lots of real-world cases. Still, it's worth taking seriously. Please don't stop either medicine on your own. Talk with your pharmacist or doctor so they can help you use them safely, and avoid driving until you know how the combination affects you.
Effect: Additive CNS depression when levocetirizine is combined with acetaminophen/codeine.
- Mechanism: Pharmacodynamic additive sedation. Codeine (an opioid; note it is a prodrug activated by CYP2D6 to morphine) depresses the CNS and respiratory drive; levocetirizine, though relatively less sedating than first-generation antihistamines, retains CNS-depressant potential.
- Direction: Increased sedation, psychomotor impairment, and potential respiratory depression.
- Evidence: Theoretical; severity rated major.
- Onset: Unspecified.
- Management: Avoid concurrent use where possible; if combined, use lowest effective doses, counsel on driving/operating machinery, and monitor for excessive sedation and respiratory compromise.
What happens
Increased risk of CNS depression
Interaction Deep Dive
Levocetirizine should not be taken together with CNS depressants, since combining them may lead to further decreases in alertness and further impairment of CNS performance1.
Why it happens (mechanism)
Additive CNS depression
How to manage this interaction
The main step here is caution and communication. The guidance on file is to avoid using these two together when possible, because the drowsiness can stack up.
- Keep taking both exactly as prescribed unless your care team tells you otherwise. Do not stop or change anything on your own.
- Ask your pharmacist or prescriber whether both are truly needed at the same time, or whether an alternative allergy medicine is a better fit.
- Your team may lower a dose or adjust timing, individualized to you, and watch you more closely.
- Avoid driving, operating machinery, or drinking alcohol until you know how the combination affects you. Seek help right away for very slow breathing or extreme drowsiness.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Acetaminophen And Codeine and Levocetirizine together?
Combining Xyzal with acetaminophen/codeine can add up to more drowsiness and slowed reactions, so talk with your pharmacist or doctor before using both, and don't drive until you know how you feel. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine 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 Acetaminophen And Codeine and Levocetirizine interaction managed?
The main step here is caution and communication. The guidance on file is to avoid using these two together when possible, because the drowsiness can stack up. Keep taking both exactly as prescribed unless your care team tells you otherwise. Do not stop or change anything on your own. Ask your pharmacist or prescriber whether both are truly needed at the same time, or whether an alternative allergy… 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 Acetaminophen And Codeine 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 Acetaminophen And Codeine
Keep reading about Levocetirizine
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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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