Drug interactions
Cimetidine + Fosamprenavir
Severity: Minor
Cimetidine and Fosamprenavir: 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 raise amprenavir levels (the active metabolite of fosamprenavir). The effect is generally small and the safety margin is reasonable.
What this interaction means in plain words
Cimetidine and Fosamprenavir have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Cimetidine may inhibit CYP3A4 metabolism of amprenavir; reduced gastric acidity may also affect absorption.
What to do
No routine adjustment is needed; monitor for amprenavir adverse effects such as rash and GI upset.
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
Frequently asked questions
Can I take Cimetidine with Fosamprenavir?
MediHelp rates the interaction as minor. Cimetidine and Fosamprenavir 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 raise amprenavir levels (the active metabolite of fosamprenavir). The effect is generally small and the safety margin is reasonable.
How serious is the interaction between Cimetidine and Fosamprenavir?
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 amprenavir adverse effects such as rash and GI upset.
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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