Drug interactions
Cimetidine + Codeine
Severity: Minor
Cimetidine and Codeine: 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 reduce conversion of codeine to morphine, potentially decreasing analgesia. The effect of cimetidine as a weak CYP2D6 inhibitor is generally modest.
What this interaction means in plain words
Cimetidine and Codeine 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; Codeine belongs to Musculoskeletal.
Why it happens
Cimetidine inhibits CYP2D6-mediated O-demethylation of codeine to morphine.
What to do
Assess analgesic response and consider a non-CYP2D6-dependent opioid if pain control is inadequate. Famotidine is an alternative acid suppressant.
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 Codeine
- Alvimopan + Codeine Contraindicated
- Codeine + Isocarboxazid Contraindicated
- Codeine + Olanzapine / samidorphan Contraindicated
- Codeine + Phenelzine Contraindicated
- Codeine + Tranylcypromine Contraindicated
- Alfentanil + Codeine Major
Frequently asked questions
Can I take Cimetidine with Codeine?
MediHelp rates the interaction as minor. Cimetidine and Codeine 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 reduce conversion of codeine to morphine, potentially decreasing analgesia. The effect of cimetidine as a weak CYP2D6 inhibitor is generally modest.
How serious is the interaction between Cimetidine and Codeine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Assess analgesic response and consider a non-CYP2D6-dependent opioid if pain control is inadequate. Famotidine is 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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