Drug interactions
Cimetidine + Efavirenz
Severity: Minor
Cimetidine and Efavirenz: 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
Efavirenz is an enzyme inducer and could modestly reduce cimetidine exposure. No meaningful clinical consequence is established.
What this interaction means in plain words
Cimetidine and Efavirenz 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; Efavirenz belongs to Anti Virals.
Why it happens
Efavirenz induces hepatic enzymes, potentially increasing cimetidine metabolism.
What to do
No action is routinely needed; assess acid-suppression response if symptoms persist.
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 Efavirenz
- Cobimetinib + Efavirenz Contraindicated
- Dienogest / estradiol valerate + Efavirenz Contraindicated
- Dihydroergotamine intranasal + Efavirenz Contraindicated
- Dihydroergotamine + Efavirenz Contraindicated
- Doravirine + Efavirenz Contraindicated
- Efavirenz + Elbasvir / grazoprevir Contraindicated
Frequently asked questions
Can I take Cimetidine with Efavirenz?
MediHelp rates the interaction as minor. Cimetidine and Efavirenz have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Efavirenz is an enzyme inducer and could modestly reduce cimetidine exposure. No meaningful clinical consequence is established.
How serious is the interaction between Cimetidine and Efavirenz?
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 action is routinely needed; assess acid-suppression response if symptoms persist.
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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