Acetaminophen And Codeine and Meclizine: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 1, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Acetaminophen And Codeine
Meclizine
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.
Your pain medicine contains codeine, an opioid, and you were also given meclizine for nausea or dizziness. Both can make you sleepy and slow your breathing, so taking them together may make those effects stronger. You could feel very drowsy, foggy, or breathe more slowly than usual.
Codeine also slows the gut, and meclizine has drying (anticholinergic) effects. Together they can cause serious constipation and trouble passing urine, and in rare cases the bowel can nearly stop moving. This concern is based on how these drugs work rather than lots of studies. The good news: your care team can manage this safely by choosing the lowest helpful dose and keeping an eye on you. Please check with your pharmacist or doctor before combining them.
Effect: Additive CNS/respiratory depression plus additive reduction in GI motility, raising risk of sedation, hypoventilation, urinary retention, severe constipation, and potentially paralytic ileus.
Mechanism: Codeine (an opioid; note it is a prodrug activated via CYP2D6 to morphine) contributes opioid CNS depression and slowed gut motility; meclizine adds sedation and anticholinergic effects. This is a pharmacodynamic, not pharmacokinetic, interaction.
- Direction: Increased combined depressant and antimotility effect.
- Onset: Unspecified.
- Evidence: Theoretical; severity rated major.
- Management: Avoid if possible; if needed, use lowest dose/shortest duration, monitor sedation, respiratory status, urinary retention, and bowel function. Consider naloxone availability.
What happens
Increased risk of paralytic ileus and an increased risk of respiratory and CNS depression
Interaction Deep Dive
Do not combine opioid-containing cough medication formulations with CNS depressants2. Codeine should be given together with CNS depressants only in patients for whom other options are insufficient. When such combined use cannot be avoided, employ the lowest effective dose for the briefest period required to reach therapeutic objectives. Furthermore, giving codeine alongside anticholinergics can heighten the likelihood of urinary retention and/or severe constipation, potentially progressing to paralytic ileus. A reduced dose of either codeine or the CNS depressant should be considered, along with vigilant monitoring for urinary retention, decreased gastric motility, sedation, and respiratory depression. Should concurrent use be justified, consider prescribing naloxone for the emergency management of opioid overdose 134.
Why it happens (mechanism)
Additive effects on gastric motility; additive CNS depression
How to manage this interaction
Keep taking both only as prescribed and do not stop or change either on your own. Your care team may reserve this combination for when other options are not enough.
- Your dose of the codeine product or the meclizine may need to be adjusted and individualized by your team, often to the lowest effective dose for the shortest time.
- Your team may monitor you more closely for heavy drowsiness, slow breathing, trouble urinating, and severe constipation.
- Tell your pharmacist or doctor if you feel very sedated, breathe slowly, cannot pass urine, or have no bowel movements.
- Ask whether having naloxone on hand is appropriate for you.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
4 reports — tap to read
a) One study found that between 2004 and 2011, the rate of emergency department visits related to nonmedical use and involving both opioid analgesics and benzodiazepines rose significantly from 11 to 34.2 per 100,000. Deaths from drug overdose attributed to prescribed and higher than prescribed doses of both drug classes also increased significantly from 0.6 to 1.7 per 100,000, and overdose deaths attributed to benzodiazepines rose significantly from 18% to 31% 2.
b) In a prospective cohort study, the rate of overdose deaths associated with the dispensing of both opioid analgesics and benzodiazepines was 10 times greater than that associated with the dispensing of opioid analgesics alone (7 vs 0.7 per 10,000 person years) 2.
c) In a cohort study using data from 2004 to 2009, the risk of fatal overdose rose significantly by 2.33 fold among patients receiving opioid analgesics who had a history of a benzodiazepine prescription, and rose by 3.86 fold among those with a current benzodiazepine prescription, compared with patients taking opioid analgesics who had no history of a benzodiazepine prescription. The risk of drug overdose deaths grew as daily benzodiazepine doses increased 2.
d) Observational studies have shown that using opioid analgesics together with benzodiazepines raises the risk of drug-related death compared with using opioid analgesics alone. Given the comparable pharmacological properties, it is reasonable to anticipate a similar risk when other CNS depressant drugs are used together with opioid analgesics 34.
Common questions
Can I take Acetaminophen And Codeine and Meclizine together?
Combining codeine (with acetaminophen) and meclizine can add up to more drowsiness, slowed breathing, and a sluggish gut, so use the lowest effective doses and have your care team monitor you. Talk to your pharmacist or doctor before taking both. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine and Meclizine 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 Meclizine interaction managed?
Keep taking both only as prescribed and do not stop or change either on your own. Your care team may reserve this combination for when other options are not enough. Your dose of the codeine product or the meclizine may need to be adjusted and individualized by your team, often to the lowest effective dose for the shortest time. Your team may monitor you more closely for heavy drowsiness, slow brea… 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 Acetaminophen And Codeine or Meclizine 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 (4)
- Product Information: CARISOPRODOL, ASPIRIN, CODEINE PHOSPHATE oral tablets, carisoprodol, aspirin, codeine phosphate oral tablets. Ingenus Pharmaceuticals LLC (per DailyMed), Orlando, FL, 2021. DailyMed
- US Food and Drug Administration (FDA): Drug Safety Communications: FDA warns about serious risks and death when combining opioid pain or cough medicines with benzodiazepines; requires its strongest warning. US Food and Drug Administration (FDA). Silver Spring, MD. 2016.
- Product Information: Codeine sulfate oral solution, codeine sulfate oral solution. Hikma Pharmaceuticals USA Inc(per FDA), Berkeley Heights, NJ, 2023. DailyMed
- Product Information: Codeine sulfate oral tablets, codeine sulfate oral tablets. Hikma Pharmaceuticals USA Inc. (per FDA), Berkeley Heights, NJ, 2023. DailyMed
Keep reading about Acetaminophen And Codeine
Keep reading about Meclizine
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