Belladonna 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
Belladonna
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.
Your pain medicine contains codeine, which can slow down your gut and make it harder to have a bowel movement or empty your bladder. Belladonna works in a similar way, calming muscle activity in your gut and bladder. When you take both together, these effects can add up and cause severe constipation or trouble urinating. In rare cases, the gut can slow down so much it nearly stops, which is called paralytic ileus.
The good news is this is manageable. Keep taking both exactly as prescribed, and let your care team know if you notice belly bloating, no bowel movements, or trouble peeing so they can keep an eye on things.
Effect: Additive decrease in GI motility and bladder tone, raising the risk of severe constipation, urinary retention, and potentially paralytic ileus.
Mechanism: Codeine (opioid) reduces gut motility and detrusor activity; belladonna alkaloids add anticholinergic slowing of smooth muscle. Effects are pharmacodynamic and additive, not metabolic. (Codeine is a prodrug activated via CYP2D6, but that is not relevant here since this is a PD interaction.)
- Direction: increased adverse GI/GU effects
- Onset: unspecified
- Evidence: theoretical
- Management: monitor for reduced bowel sounds, abdominal distension, constipation, and urinary retention; individualize dosing and consider bowel regimen. Severity: major.
What happens
An increased risk of paralytic ileus
Interaction Deep Dive
Concomitant use of codeine with anticholinergic drugs may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Monitor patients for signs of urinary retention or reduced gastric motility when codeine is used concomitantly with anticholinergic drugs1.
Why it happens (mechanism)
Additive effects on gastric motility
How to manage this interaction
This combination can be managed with awareness and monitoring. Do not start or stop either medicine on your own.
- Keep taking both as prescribed unless your prescriber tells you otherwise.
- Your care team may monitor you more closely for constipation or trouble urinating, and your doses may be adjusted and individualized if needed.
- Watch for no bowel movements, belly swelling or pain, or difficulty peeing, and report these promptly.
- Staying hydrated and asking whether a stool softener is appropriate can help.
Raise any of these symptoms with your pharmacist or doctor right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Belladonna and Acetaminophen And Codeine together?
Taking codeine (in your acetaminophen-codeine product) with belladonna can add up to cause severe constipation or urinary retention, so watch for these and tell your care team if they happen. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Belladonna 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 Belladonna and Acetaminophen And Codeine interaction managed?
This combination can be managed with awareness and monitoring. Do not start or stop either medicine on your own. Keep taking both as prescribed unless your prescriber tells you otherwise. Your care team may monitor you more closely for constipation or trouble urinating, and your doses may be adjusted and individualized if needed. Watch for no bowel movements, belly swelling or pain, or difficulty… 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 Belladonna 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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