Amifampridine 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
Amifampridine
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 amifampridine (a medicine for a rare muscle condition) along with a pain medicine that combines acetaminophen and codeine. When these are taken together, there may be a higher chance of having a seizure.
I want to be honest with you: this warning is based on caution rather than strong proof, and we don't fully know the exact reason. Amifampridine on its own can lower the point at which a seizure might happen, so the concern is about adding to that. The good news is your care team can manage this. Please keep taking both exactly as prescribed, and let your doctor or pharmacist know if you notice any twitching, unusual shaking, or a seizure.
Effect: Potential additive lowering of the seizure threshold with concomitant amifampridine and acetaminophen/codeine, giving an increased seizure risk.
- Mechanism: Unknown; amifampridine is known to be dose-dependently proconvulsant.
- Direction/magnitude: Additive pharmacodynamic risk; magnitude not quantified.
- Onset: Unspecified.
- Evidence: Theoretical.
- Severity: Major.
Management: Weigh the seizure risk before combining. If used together, dose amifampridine conservatively (its labeling already limits dosing by seizure risk), monitor for seizure activity, and counsel the patient. Escalate promptly if any seizure or myoclonus occurs.
What happens
Increased risk of seizures
Interaction Deep Dive
Concomitant use of amifampridine and this drug may increase the risk of seizures. Consider this risk if these agents are to be used concomitantly1.
Why it happens (mechanism)
Unknown
How to manage this interaction
Keep taking both medicines as prescribed unless your doctor tells you otherwise. This concern is theoretical, and your care team can manage it.
- Your team will weigh whether the two are needed together, and may adjust and individualize your dose (amifampridine dosing is already guided by seizure risk).
- They may monitor you more closely for any signs of a seizure.
- Tell your pharmacist or prescriber right away about any twitching, jerking, confusion, or a seizure.
- Ask before starting any new medicines, since some can add to seizure risk.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Amifampridine and Acetaminophen And Codeine together?
Taking amifampridine with acetaminophen/codeine may add to the risk of seizures, so keep both as prescribed and report any twitching or seizure activity to your care team, who can adjust dosing and monitor you. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amifampridine 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 Amifampridine and Acetaminophen And Codeine interaction managed?
Keep taking both medicines as prescribed unless your doctor tells you otherwise. This concern is theoretical, and your care team can manage it. Your team will weigh whether the two are needed together, and may adjust and individualize your dose (amifampridine dosing is already guided by seizure risk). They may monitor you more closely for any signs of a seizure. Tell your pharmacist or prescriber… 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 Amifampridine 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: FIRDAPSE(R) oral tablets, amifampridine oral tablets. Catalyst Pharmaceuticals Inc (per manufacturer), Coral Gables, FL, 2018. DailyMed
Keep reading about Acetaminophen And Codeine
Keep reading about Amifampridine
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