Alosetron 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
Alosetron
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 two medicines are acetaminophen with codeine (a pain reliever) and alosetron (used for certain bowel problems). Both can raise a brain chemical called serotonin. When two medicines do this at the same time, there is a small chance of a reaction called serotonin syndrome.
Signs to watch for include feeling agitated or confused, a fast heartbeat, sweating, shivering, muscle twitching, or shaking. This is considered a theoretical concern, meaning it hasn't been clearly seen with these two together, but it's worth knowing. Keep taking both as prescribed, and let your pharmacist or doctor know right away if you notice these symptoms. Your care team can manage this safely.
Effect: Additive serotonergic activity may increase the risk of serotonin syndrome. Codeine has weak serotonergic properties, and alosetron acts on the 5-HT3 system; combined use theoretically elevates serotonergic tone.
- Direction: Additive PD effect, not a metabolic (CYP) interaction.
- Severity: Major. Onset: Unspecified. Evidence: Theoretical.
- Management: If concurrent use is required, monitor for autonomic instability, neuromuscular changes (clonus, hyperreflexia, rigidity), and mental status changes, especially at initiation and dose adjustment. Discontinue codeine if serotonin syndrome is suspected.
Acetaminophen is not implicated in this interaction.
What happens
Increased risk of serotonin syndrome
Interaction Deep Dive
Coadministration of alosetron and codeine may result in serotonin syndrome, because both drugs affect the serotonergic neurotransmitter system. If concomitant use of codeine and such an agent is clinically required, monitor patients carefully, especially during treatment initiation and dosage adjustment. Discontinue codeine if serotonin syndrome is suspected1.
Why it happens (mechanism)
Additive serotonergic effect
How to manage this interaction
You can usually take both medicines when your care team decides you need them. Here's how this is typically handled:
- Keep taking both as prescribed unless your prescriber tells you otherwise.
- Your team may monitor you more closely, especially when you first start or when a dose changes.
- Watch for symptoms like agitation, confusion, fast heartbeat, sweating, shivering, muscle twitching, or shaking.
Contact your pharmacist or doctor if you have questions, and seek care promptly if these symptoms appear. The codeine may be stopped if serotonin syndrome is suspected, which is a decision your care team will make.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Alosetron and Acetaminophen And Codeine together?
Taking codeine (in acetaminophen-codeine) with alosetron may slightly raise the risk of serotonin syndrome, a theoretical concern. Keep taking both as prescribed and tell your care team right away if you feel agitated, confused, sweaty, shaky, or have a racing heartbeat. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Alosetron 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 Alosetron and Acetaminophen And Codeine interaction managed?
You can usually take both medicines when your care team decides you need them. Here's how this is typically handled: Keep taking both as prescribed unless your prescriber tells you otherwise. Your team may monitor you more closely, especially when you first start or when a dose changes. Watch for symptoms like agitation, confusion, fast heartbeat, sweating, shivering, muscle twitching, or shaking.… 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 Alosetron 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
Keep reading about Acetaminophen And Codeine
Keep reading about Alosetron
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.
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