Acetaminophen And Codeine and Lasmiditan: 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
Lasmiditan
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, and Reyvow (lasmiditan) is used for migraine. Both can gently 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 can include feeling agitated or confused, shivering or muscle twitching, sweating, a fast heartbeat, or a high fever.
This is mostly a theoretical concern, so please don't panic. Many people take medicines like these safely. Just keep taking both as prescribed and let your pharmacist or doctor know you use them together so they can watch out for you.
Interaction: Additive serotonergic effects between codeine (weak serotonergic opioid) and lasmiditan (5-HT1F agonist) may increase risk of serotonin syndrome (hypertension, hyperthermia, myoclonus, autonomic and mental status changes).
- Direction: Pharmacodynamic (additive), not a CYP/prodrug-activation issue; risk is increased serotonergic tone.
- Evidence: Theoretical; onset unspecified.
- Severity: Major.
- Management: Use lasmiditan with caution when combined with serotonergic agents. Monitor for signs/symptoms of serotonin syndrome, especially after dose initiation or increase. Discontinue lasmiditan (and serotonergic agent) if serotonin syndrome is suspected.
What happens
Increased risk of serotonin syndrome (hypertension, hyperthermia, myoclonus, mental status changes)
Interaction Deep Dive
As a serotonin agonist, lasmiditan carries an elevated risk of serotonin syndrome when given together with another serotonergic drug. Exercise caution when using lasmiditan in patients who are receiving agents that raise serotonin levels, and stop lasmiditan if serotonin syndrome is suspected1.
Why it happens (mechanism)
Additive serotonergic effects
How to manage this interaction
Good news: your care team can manage this by keeping an eye out and adjusting if needed.
- Keep taking both as prescribed unless your prescriber tells you otherwise.
- Your team may monitor you more closely, especially when either medicine is started or a dose changes.
- Learn the warning signs: agitation, confusion, muscle twitching or stiffness, shivering, sweating, fast heartbeat, or fever.
Get urgent care right away if several of these appear together. Tell your pharmacist or doctor that you take both, and ask whether a different migraine or pain option might suit you better.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Acetaminophen And Codeine and Lasmiditan together?
Taking codeine-containing pain medicine with lasmiditan (Reyvow) may slightly raise the risk of serotonin syndrome. Keep taking both as prescribed, know the warning signs, and get urgent care if they appear together. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine and Lasmiditan 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 Lasmiditan interaction managed?
Good news: your care team can manage this by keeping an eye out and adjusting if needed. Keep taking both as prescribed unless your prescriber tells you otherwise. Your team may monitor you more closely, especially when either medicine is started or a dose changes. Learn the warning signs: agitation, confusion, muscle twitching or stiffness, shivering, sweating, fast heartbeat, or fever. Get urgen… 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 Lasmiditan 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: REYVOW(TM) oral tablets, lasmiditan oral tablets. Lilly USA LLC (per manufacturer), Indianapolis, IN, 2019. DailyMed
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