Drug interactions
Cimetidine + Primidone
Severity: Minor
Cimetidine and Primidone: 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
Primidone, partly converted to phenobarbital, may induce enzymes and modestly reduce cimetidine exposure. Cimetidine may raise primidone levels. Significance is limited.
What this interaction means in plain words
Cimetidine and Primidone 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; Primidone belongs to Central Nervous System.
Why it happens
Enzyme induction by primidone and its phenobarbital metabolite increases cimetidine clearance; cimetidine inhibits CYP metabolism of primidone.
What to do
No routine adjustment is needed; monitor for sedation and, if signs appear, anticonvulsant levels.
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 Primidone
- Lorlatinib + Primidone Contraindicated
- Lurasidone + Primidone Contraindicated
- Primidone + Ranolazine Contraindicated
- Primidone + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Primidone + Voriconazole Contraindicated
- Abiraterone + Primidone Major
Frequently asked questions
Can I take Cimetidine with Primidone?
MediHelp rates the interaction as minor. Cimetidine and Primidone have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Primidone, partly converted to phenobarbital, may induce enzymes and modestly reduce cimetidine exposure. Cimetidine may raise primidone levels. Significance is limited.
How serious is the interaction between Cimetidine and Primidone?
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 adjustment is needed; monitor for sedation and, if signs appear, anticonvulsant levels.
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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