Acetaminophen And Codeine and Thiothixene: 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
Thiothixene
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 pee. Thiothixene also has drying (anticholinergic) effects that slow the gut and bladder. Taken together, these two can add up and may lead to bad constipation or trouble urinating. In rare cases, the bowel can slow down so much that it nearly stops, which is called paralytic ileus.
This concern is based mostly on how these drugs work, not on lots of reported cases. Still, it is worth watching. The good news is your care team can manage this easily by keeping an eye on things, so please talk with your pharmacist or doctor if you notice changes.
Effect: Additive reduction in GI motility and bladder tone with concurrent codeine (opioid) and thiothixene (typical antipsychotic with anticholinergic activity), increasing risk of severe constipation, urinary retention, and potentially paralytic ileus.
Mechanism: Pharmacodynamic additive effect. Codeine slows gastric/intestinal motility via opioid receptors; thiothixene contributes anticholinergic inhibition of smooth muscle and detrusor function.
- Direction: Increased anticholinergic/constipating burden (PD, not PK).
- Onset: Unspecified.
- Evidence: Theoretical.
- Management: Monitor for reduced bowel motility, abdominal distension, and urinary retention. Ensure bowel regimen/hydration; dose individualized by the care team.
What happens
An increased risk of paralytic ileus
Interaction Deep Dive
When codeine is taken together with anticholinergic agents, there may be a heightened risk of urinary retention and/or serious constipation, potentially progressing to paralytic ileus. During such concurrent use of codeine and anticholinergic drugs, patients should be observed for indications of urinary retention or diminished gastric motility1.
Why it happens (mechanism)
Additive effects on gastric motility
How to manage this interaction
Keep taking both medicines as prescribed unless your care team tells you otherwise. Your team can manage this combination by watching for signs the two drugs are adding up.
- Watch for: constipation that is not improving, hard or absent bowel movements, belly bloating or pain, or trouble urinating.
- Helpful habits: stay hydrated and keep moving as you are able; your team may suggest a bowel routine.
- Speak up: tell your pharmacist or prescriber promptly if these symptoms appear.
Doses may be adjusted and individualized by your care team, and they may monitor you more closely while you use both.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Acetaminophen And Codeine and Thiothixene together?
Combining codeine with thiothixene can add up to cause severe constipation or urinary retention, so watch for these symptoms and report them; your care team can manage this with monitoring and adjustments. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine and Thiothixene 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 Thiothixene interaction managed?
Keep taking both medicines as prescribed unless your care team tells you otherwise. Your team can manage this combination by watching for signs the two drugs are adding up. Watch for: constipation that is not improving, hard or absent bowel movements, belly bloating or pain, or trouble urinating. Helpful habits: stay hydrated and keep moving as you are able; your team may suggest a bowel routine.… 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 Thiothixene 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
Keep reading about Acetaminophen And Codeine
Keep reading about Thiothixene
These medications also interact with supplements
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist