Drug interactions
Amitriptyline + Cimetidine
Severity: Moderate
Amitriptyline and Cimetidine: moderate 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 increases plasma concentrations of tricyclic antidepressants including amitriptyline. This can produce anticholinergic effects, sedation, arrhythmia and QT prolongation.
What this interaction means in plain words
Amitriptyline and Cimetidine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Amitriptyline belongs to Central Nervous System; Cimetidine belongs to Gastrointestinal Tract.
Why it happens
Cimetidine inhibits hepatic CYP enzymes (including CYP2D6, CYP2C19 and CYP3A4) that metabolize amitriptyline.
What to do
Monitor for anticholinergic and cardiac toxicity and consider tricyclic dose reduction, with plasma levels or ECG if needed. Prefer famotidine or another H2 blocker without enzyme inhibition.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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 Amitriptyline
- Amitriptyline + Isocarboxazid Contraindicated
- Amitriptyline + Methylene blue Contraindicated
- Amitriptyline + Phenelzine Contraindicated
- Amitriptyline + Pimozide Contraindicated
- Amitriptyline + Procarbazine Contraindicated
- Amitriptyline + Safinamide Contraindicated
Frequently asked questions
Can I take Amitriptyline with Cimetidine?
MediHelp rates the interaction as moderate. Amitriptyline and Cimetidine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Cimetidine increases plasma concentrations of tricyclic antidepressants including amitriptyline. This can produce anticholinergic effects, sedation, arrhythmia and QT prolongation.
How serious is the interaction between Amitriptyline and Cimetidine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for anticholinergic and cardiac toxicity and consider tricyclic dose reduction, with plasma levels or ECG if needed. Prefer famotidine or another H2 blocker without enzyme inhibition.
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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