Donepezil 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
Donepezil
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 donepezil (for memory) along with acetaminophen and codeine (for pain). Both of these medicines can, in theory, make the brain a little more likely to have a seizure. When taken together, that small effect could add up.
I want to be clear: this is a theoretical concern, meaning it's based on how the drugs work rather than lots of real-world reports. Most people take these without a problem. Your care team can manage this easily, often by starting at a low dose and adjusting slowly. Just let your pharmacist or doctor know you're on both, and tell them right away if you notice any unusual shaking, twitching, or a seizure.
Effect: Additive lowering of seizure threshold when donepezil is combined with codeine/acetaminophen.
- Mechanism: Donepezil has been associated with seizure threshold reduction; opioids (codeine) can also lower seizure threshold. Combined use is theoretically additive. Precise mechanism unknown.
- Direction: Pharmacodynamic additive CNS effect, not a PK interaction (note codeine is a CYP2D6 prodrug, but that is not the basis of this interaction).
- Evidence: Theoretical; severity rated major.
- Onset: Unspecified.
- Management: Use caution, initiate donepezil low and titrate gradually, monitor for seizure activity, especially in patients with a seizure history.
What happens
Reduced seizure threshold
Interaction Deep Dive
Seizure threshold lowering effects have been associated with donepezil1. Use extreme caution when prescribing donepezil with drugs that lower seizure threshold (eg, antipsychotics, antidepressants, theophylline, systemic corticosteroids). Begin treatment with a low initial dose and increase dose gradually.
Why it happens (mechanism)
Unknown
How to manage this interaction
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. This concern is theoretical, and your care team can manage it.
- Your team may start donepezil at a low dose and increase it slowly to reduce risk.
- They may monitor you more closely, especially if you have a history of seizures.
- Make sure your pharmacist and doctor know you take both, plus any other medicines that can affect seizures (some antidepressants, antipsychotics, or steroids).
- Seek help right away for any seizure, unusual twitching, or confusion.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Donepezil and Acetaminophen And Codeine together?
Donepezil and codeine can each slightly lower the seizure threshold, so together the risk may add up, though this is only a theoretical concern. Your care team can manage it by starting donepezil low, titrating slowly, and watching for any seizure symptoms. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Donepezil 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 Donepezil and Acetaminophen And Codeine interaction managed?
Keep taking both medicines as prescribed unless your prescriber tells you otherwise. This concern is theoretical, and your care team can manage it. Your team may start donepezil at a low dose and increase it slowly to reduce risk. They may monitor you more closely, especially if you have a history of seizures. Make sure your pharmacist and doctor know you take both, plus any other medicines that c… 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.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Donepezil 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: NAMZARIC oral capsules, memantine HCl extended-release donepezil HCl oral capsules. Forest Laboratories LLC (per manufacturer), St. Louis, MO, 2014. DailyMed
Keep reading about Acetaminophen And Codeine
Keep reading about Donepezil
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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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