Acetaminophen And Codeine and Protriptyline: 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
Protriptyline
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 medicine) along with protriptyline (an older antidepressant). Both can affect your body in overlapping ways, so using them together needs a little extra care.
First, both can nudge up serotonin levels in the brain. Rarely, this can cause serotonin syndrome, with symptoms like agitation, fast heartbeat, sweating, shakiness, or confusion. Second, both can slow down your gut and bladder, which can lead to bad constipation or trouble urinating, and in severe cases the gut can stop moving. The good news: this is a theoretical concern, and your care team can manage it by watching you closely, especially when you start or change doses.
Effect: Additive risk of serotonin syndrome and of paralytic ileus.
- Mechanism: Additive serotonergic effects (codeine and protriptyline both raise serotonergic tone) plus additive reduction in GI motility (opioid effect on codeine, anticholinergic effect of the TCA protriptyline), increasing risk of urinary retention, severe constipation, and paralytic ileus.
- Direction: Additive/pharmacodynamic; not a metabolic prodrug issue.
- Evidence: Theoretical. Severity: Major. Onset: Unspecified.
- Management: If used together, monitor for urinary retention, severe constipation, and serotonin syndrome (autonomic instability, neuromuscular excitability, mental status change), particularly at initiation and dose changes. Discontinue codeine if serotonin syndrome is suspected.
What happens
Increased risk of paralytic ileus; increased risk of serotonin syndrome
Interaction Deep Dive
Serotonin syndrome has been reported when opioids like codeine are taken together with serotonergic agents. Combining codeine with anticholinergic drugs can also heighten the likelihood of urinary retention and severe constipation, potentially progressing to paralytic ileus. When such combined use is necessary, monitor the patient carefully for urinary retention, severe constipation, and the signs and symptoms of serotonin syndrome1 during the start of therapy and when doses are being adjusted. Codeine should be stopped if serotonin syndrome is suspected 2.
Why it happens (mechanism)
Additive effects on gastric motility; additive serotonergic effects
How to manage this interaction
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. This is a precaution, not a reason to stop on your own.
- Watch for signs of serotonin syndrome: agitation, confusion, fast heartbeat, sweating, tremor, or muscle twitching. Get urgent help if these appear.
- Watch for severe constipation or trouble urinating. Tell your care team promptly.
- Your team may monitor you more closely and individualize your doses, especially when starting or changing either medicine.
- Ask your pharmacist or doctor before adding other serotonin-raising or gut-slowing medicines.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Acetaminophen And Codeine and Protriptyline together?
Taking acetaminophen/codeine with protriptyline can add up to a higher risk of serotonin syndrome and severe gut or bladder slowing; keep taking both as prescribed but watch for warning signs and let your care team monitor you closely. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine and Protriptyline 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 Protriptyline interaction managed?
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. This is a precaution, not a reason to stop on your own. Watch for signs of serotonin syndrome: agitation, confusion, fast heartbeat, sweating, tremor, or muscle twitching. Get urgent help if these appear. Watch for severe constipation or trouble urinating. Tell your care team promptly. Your team may monitor you mo… 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 Protriptyline 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 (2)
- Product Information: Codeine sulfate oral tablets, codeine sulfate oral tablets. West-Ward Pharmaceuticals Corp (per DailyMed), Eatontown, NJ, 2016. DailyMed
- Product Information: CARISOPRODOL, ASPIRIN, CODEINE PHOSPHATE oral tablets, carisoprodol, aspirin, codeine phosphate oral tablets. Ingenus Pharmaceuticals LLC (per DailyMed), Orlando, FL, 2021. DailyMed
Keep reading about Acetaminophen And Codeine
Keep reading about Protriptyline
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