Acetaminophen And Codeine and Milnacipran: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 1, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Acetaminophen And Codeine
Milnacipran
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.
Both of these medicines can raise serotonin, a natural brain chemical. Milnacipran (Savella) is used for fibromyalgia and works by increasing serotonin and norepinephrine. Codeine (an opioid pain reliever, combined here with acetaminophen) can also nudge serotonin levels up a little. When you take them together, those effects can add up.
In rare cases this can lead to serotonin syndrome, which may cause things like a fast heartbeat, shivering, sweating, agitation, muscle twitching, or feeling confused. This is mostly a theoretical concern, but it is worth knowing about. Do not stop either medicine on your own. Just let your doctor or pharmacist know you take both so they can keep an eye on you, especially when starting or changing doses.
Effect: Additive serotonergic activity may increase the risk of serotonin syndrome when codeine is combined with milnacipran, an SNRI.
- Mechanism: Additive central serotonergic effects (milnacipran inhibits serotonin/norepinephrine reuptake; codeine has weak serotonergic activity).
- Direction: Increased serotonergic tone; risk is additive, not a PK interaction.
- Evidence: Theoretical; severity rated major.
- Onset: Unspecified; highest risk at initiation and dose escalation.
- Management: Observe for clonus, hyperthermia, autonomic instability, agitation, hyperreflexia. Discontinue codeine if serotonin syndrome is suspected.
What happens
Increased risk of serotonin syndrome
Interaction Deep Dive
Serotonin syndrome has occurred when opioids like codeine are taken together with serotonergic agents. When such combined use is required, monitor the patient closely, especially when starting therapy and when doses are being changed. Should serotonin syndrome be suspected, stop codeine123.
Why it happens (mechanism)
Additive serotonergic effects
How to manage this interaction
This combination can usually be used with monitoring. Keep taking both medicines exactly as prescribed unless your care team tells you otherwise.
- Your team may watch you more closely, especially when you start milnacipran or codeine or when a dose is changed.
- Watch for warning signs like a racing heart, fever, sweating, shivering, muscle twitching or stiffness, restlessness, or confusion.
- If these happen, seek medical care promptly. Your doctor may stop the codeine if serotonin syndrome is suspected.
Ask your pharmacist or prescriber before adding any other serotonin-raising medicine.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
Common questions
Can I take Acetaminophen And Codeine and Milnacipran together?
Taking codeine (with acetaminophen) alongside milnacipran can add up serotonin effects and, rarely, cause serotonin syndrome. Keep both as prescribed, watch for symptoms, and tell your care team so they can monitor you. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen And Codeine and Milnacipran 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 Milnacipran interaction managed?
This combination can usually be used with monitoring. Keep taking both medicines exactly as prescribed unless your care team tells you otherwise. Your team may watch you more closely, especially when you start milnacipran or codeine or when a dose is changed. Watch for warning signs like a racing heart, fever, sweating, shivering, muscle twitching or stiffness, restlessness, or confusion. If these… 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 Milnacipran 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 (3)
- Product Information: Codeine sulfate oral tablets, codeine sulfate oral tablets. West-Ward Pharmaceuticals Corp (per DailyMed), Eatontown, NJ, 2016. DailyMed
- Product Information: Codeine sulfate oral solution, codeine sulfate oral solution. Hikma Pharmaceuticals USA Inc(per FDA), Berkeley Heights, NJ, 2023. DailyMed
- Product Information: Codeine sulfate oral tablets, codeine sulfate oral tablets. Hikma Pharmaceuticals USA Inc. (per FDA), Berkeley Heights, NJ, 2023. DailyMed
Keep reading about Acetaminophen And Codeine
Keep reading about Milnacipran
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