Cetirizine and Acetaminophen And Codeine: 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
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.
Both of these medicines can make you feel sleepy or slow. Your acetaminophen and codeine is a pain reliever, and codeine is an opioid that can cause drowsiness. Cetirizine (Zyrtec) is an allergy medicine that, while less sedating than older antihistamines, can still make some people tired. Taken together, those calming effects can add up. You might feel more drowsy, foggy, or less alert than usual, which matters for things like driving.
The good news is this is easy to manage. Talk with your pharmacist or doctor about taking both, and don't stop either medicine on your own. They can help you use them safely.
Effect: Additive CNS depression from combining codeine (opioid) with cetirizine (second-generation H1 antihistamine).
- Mechanism: Pharmacodynamic additive sedation; no significant PK interaction. Neither agent's effect here depends on prodrug activation for this interaction.
- Direction/magnitude: Increased sedation, reduced alertness, and psychomotor impairment. Magnitude unspecified; cetirizine is less sedating than first-generation agents.
- Onset: Unspecified.
- Evidence: Theoretical.
- Management: Use with caution; counsel on additive drowsiness and impaired driving. Monitor for excess sedation and respiratory depression; individualize dosing per care team.
What happens
Increased risk of CNS depression
Interaction Deep Dive
Avoid concurrent use of cetirizine hydrochloride with CNS depressants, such as this drug, because additional reduction in alertness and additional impairment of CNS performance may occur1.
Why it happens (mechanism)
Additive CNS depression
How to manage this interaction
If both medicines are prescribed or recommended for you, keep taking them as directed and don't stop on your own.
- Be aware you may feel more drowsy or less alert, especially when you first combine them.
- Use caution with driving or operating machinery until you know how the combination affects you.
- Avoid adding alcohol or other sedating products without checking first.
- Ask your pharmacist or prescriber whether a non-drowsy allergy option might suit you better, and let them know if the sleepiness feels excessive.
Your care team can adjust and individualize things and monitor you more closely if needed.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Cetirizine and Acetaminophen And Codeine together?
Taking acetaminophen/codeine with cetirizine can add up to extra drowsiness and reduced alertness, so use caution (especially driving) and check with your pharmacist or doctor about the safest plan. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Cetirizine and Acetaminophen And Codeine 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 Cetirizine and Acetaminophen And Codeine interaction managed?
If both medicines are prescribed or recommended for you, keep taking them as directed and don't stop on your own. Be aware you may feel more drowsy or less alert, especially when you first combine them. Use caution with driving or operating machinery until you know how the combination affects you. Avoid adding alcohol or other sedating products without checking first. Ask your pharmacist or prescr… 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.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Cetirizine or Acetaminophen And Codeine 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: QUZYTTIR(TM) intravenous injection, cetirizine hydrochloride intravenous injection. TerSera Therapeutics LLC (per FDA), Lake Forest, IL, 2019. DailyMed
Keep reading about Acetaminophen And Codeine
Keep reading about Cetirizine
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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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