Drug interactions
Cimetidine + Ivacaftor
Severity: Minor
Cimetidine and Ivacaftor: 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
Ivacaftor weakly inhibits P-glycoprotein and could slightly raise levels of P-gp substrates. Cimetidine is not a sensitive P-gp substrate, so a meaningful effect is unlikely.
What this interaction means in plain words
Cimetidine and Ivacaftor 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; Ivacaftor belongs to Miscellaneous.
Why it happens
Ivacaftor and its M1 metabolite weakly inhibit P-gp, which could marginally raise cimetidine exposure.
What to do
No dose adjustment is needed; monitor routinely for cimetidine adverse effects.
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 Ivacaftor
- Ensitrelvir + Ivacaftor Contraindicated
- Apalutamide + Ivacaftor Major
- Carbamazepine + Ivacaftor Major
- Clarithromycin + Ivacaftor Major
- Efavirenz + Ivacaftor Major
- Enzalutamide + Ivacaftor Major
Frequently asked questions
Can I take Cimetidine with Ivacaftor?
MediHelp rates the interaction as minor. Cimetidine and Ivacaftor have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Ivacaftor weakly inhibits P-glycoprotein and could slightly raise levels of P-gp substrates. Cimetidine is not a sensitive P-gp substrate, so a meaningful effect is unlikely.
How serious is the interaction between Cimetidine and Ivacaftor?
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 dose adjustment is needed; monitor routinely for cimetidine adverse effects.
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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