Drug interactions
Cimetidine + Donepezil
Severity: Minor
Cimetidine and Donepezil: minor interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Cimetidine may increase donepezil concentrations, which could enhance cholinergic effects such as nausea, bradycardia and diarrhea. The effect is expected to be modest.
What this interaction means in plain words
Cimetidine and Donepezil have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Cimetidine belongs to Gastrointestinal Tract; Donepezil belongs to Central Nervous System.
Why it happens
Cimetidine weakly inhibits CYP3A4 and CYP2D6, which contribute to donepezil metabolism.
What to do
No routine dose change is needed. Watch for bradycardia and gastrointestinal intolerance, and use famotidine if an acid suppressant is required.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Cimetidine
- Cimetidine + Dofetilide Contraindicated
- Cimetidine + Fezolinetant Contraindicated
- Alfentanil + Cimetidine Major
- Atazanavir + Cimetidine Major
- Carmustine + Cimetidine Major
- Cimetidine + Citalopram Major
Other interactions of Donepezil
- Donepezil + Dronedarone Contraindicated
- Donepezil + Pimozide Contraindicated
- Donepezil + Thioridazine Contraindicated
- Donepezil + Vandetanib Contraindicated
- Amiodarone + Donepezil Major
- Amisulpride + Donepezil Major
Frequently asked questions
Can I take Cimetidine with Donepezil?
MediHelp rates the interaction as minor. Cimetidine and Donepezil have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Cimetidine may increase donepezil concentrations, which could enhance cholinergic effects such as nausea, bradycardia and diarrhea. The effect is expected to be modest.
How serious is the interaction between Cimetidine and Donepezil?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine dose change is needed. Watch for bradycardia and gastrointestinal intolerance, and use famotidine if an acid suppressant is required.
What other medicines interact with Cimetidine?
MediHelp also lists interactions of Cimetidine with, for example, Dofetilide, Fezolinetant, Alfentanil. The full list is on the Cimetidine page.
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