Drug interactions
Cimetidine + Citalopram
Severity: Major
Cimetidine and Citalopram: major 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 raises citalopram concentrations, increasing the risk of QT prolongation and serotonergic adverse effects. Labeling advises a lower maximum citalopram dose with CYP2C19 inhibitors.
What this interaction means in plain words
Cimetidine and Citalopram can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Cimetidine belongs to Gastrointestinal Tract; Citalopram belongs to Central Nervous System.
Why it happens
Cimetidine inhibits CYP2C19 and CYP3A4, reducing citalopram metabolism.
What to do
Limit citalopram to 20 mg daily and consider ECG monitoring, especially with other QT risks. Use famotidine as an alternative acid suppressant.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Cimetidine
- Cimetidine + Dofetilide Contraindicated
- Cimetidine + Fezolinetant Contraindicated
- Alfentanil + Cimetidine Major
- Atazanavir + Cimetidine Major
- Carmustine + Cimetidine Major
- Cimetidine + Clozapine Major
Other interactions of Citalopram
- Cisapride + Citalopram Contraindicated
- Citalopram + Dronedarone Contraindicated
- Citalopram + Escitalopram Contraindicated
- Citalopram + Isocarboxazid Contraindicated
- Citalopram + Methylene blue Contraindicated
- Citalopram + Phenelzine Contraindicated
Frequently asked questions
Can I take Cimetidine with Citalopram?
MediHelp rates the interaction as major. Cimetidine and Citalopram can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Cimetidine raises citalopram concentrations, increasing the risk of QT prolongation and serotonergic adverse effects. Labeling advises a lower maximum citalopram dose with CYP2C19 inhibitors.
How serious is the interaction between Cimetidine and Citalopram?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Limit citalopram to 20 mg daily and consider ECG monitoring, especially with other QT risks. Use famotidine as an alternative acid suppressant.
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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