Mepenzolate 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
Mepenzolate
No brand names on record
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.
You've been prescribed acetaminophen with codeine (a pain reliever) and mepenzolate (a medicine that calms the gut and belongs to a group called anticholinergics). Both of these can slow down how your bowels move and can make it harder to empty your bladder.
When you take them together, those effects can add up. That can mean more constipation or trouble urinating. In rare cases, the gut can slow so much that it nearly stops, which is called paralytic ileus. This is a theoretical concern, not something proven to happen often. The good news is your care team can manage this by watching you closely, so please keep taking both as prescribed and tell them about any severe constipation or bloating.
Effect: Additive risk of urinary retention, severe constipation, and potentially paralytic ileus when codeine (opioid, slows GI motility) is combined with mepenzolate (an anticholinergic/antimuscarinic agent that also reduces gut motility and bladder emptying).
- Mechanism: Additive depression of gastric and intestinal motility plus antimuscarinic effects on bladder function. Neither drug is a prodrug relevant to this PD interaction.
- Direction/magnitude: Pharmacodynamic, additive; magnitude not quantified.
- Onset: Unspecified.
- Evidence: Theoretical.
- Management: Monitor for reduced gastric motility, abdominal distension, and urinary retention. Ensure bowel regimen; individualize therapy.
What happens
An increased risk of paralytic ileus
Interaction Deep Dive
Taking codeine together with anticholinergic agents can heighten the likelihood of urinary retention and/or severe constipation, potentially progressing to paralytic ileus. When codeine and anticholinergic drugs are given together, watch patients for indications of urinary retention or diminished gastric motility1.
Why it happens (mechanism)
Additive effects on gastric motility
How to manage this interaction
Both medicines can slow the gut and the bladder, so the main step your care team takes is watching you more closely rather than avoiding the combination outright.
- Keep taking both as prescribed unless your doctor or pharmacist tells you otherwise.
- Watch for severe or worsening constipation, bloating, belly pain, or trouble passing urine, and report these promptly.
- Staying hydrated and moving around can help keep your bowels active; ask your pharmacist whether a stool softener or laxative is appropriate for you.
- Your doses may be adjusted and individualized by your care team if needed.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Mepenzolate and Acetaminophen And Codeine together?
Taking codeine with mepenzolate can add up to more constipation and trouble urinating, and rarely a badly slowed gut. Keep taking both as prescribed, but tell your care team about severe constipation, bloating, or trouble urinating. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Mepenzolate 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 Mepenzolate and Acetaminophen And Codeine interaction managed?
Both medicines can slow the gut and the bladder, so the main step your care team takes is watching you more closely rather than avoiding the combination outright. Keep taking both as prescribed unless your doctor or pharmacist tells you otherwise. Watch for severe or worsening constipation, bloating, belly pain, or trouble passing urine, and report these promptly. Staying hydrated and moving aroun… 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 Mepenzolate 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: CARISOPRODOL, ASPIRIN, CODEINE PHOSPHATE oral tablets, carisoprodol, aspirin, codeine phosphate oral tablets. Ingenus Pharmaceuticals LLC (per DailyMed), Orlando, FL, 2021. DailyMed
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