Drug interactions
Cimetidine + Erlotinib
Severity: Moderate
Cimetidine and Erlotinib: moderate 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 reduces gastric acidity, which lowers the absorption of erlotinib and may decrease its effectiveness. Cimetidine may also affect erlotinib clearance through CYP inhibition, though the net effect is a reduction in exposure.
What this interaction means in plain words
Cimetidine and Erlotinib can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Cimetidine belongs to Gastrointestinal Tract; Erlotinib belongs to Oncology.
Why it happens
Erlotinib solubility is pH-dependent, so raised gastric pH reduces its absorption.
What to do
Avoid the combination if possible. If an H2 antagonist is needed, give erlotinib at least 10 hours after the evening dose and at least 2 hours before the next dose.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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 Erlotinib
- Amobarbital + Erlotinib Major
- Apalutamide + Erlotinib Major
- Carbamazepine + Erlotinib Major
- Cobicistat + Erlotinib Major
- Darunavir + Erlotinib Major
- Dexlansoprazole + Erlotinib Major
Frequently asked questions
Can I take Cimetidine with Erlotinib?
MediHelp rates the interaction as moderate. Cimetidine and Erlotinib can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Cimetidine reduces gastric acidity, which lowers the absorption of erlotinib and may decrease its effectiveness. Cimetidine may also affect erlotinib clearance through CYP inhibition, though the net effect is a reduction in exposure.
How serious is the interaction between Cimetidine and Erlotinib?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination if possible. If an H2 antagonist is needed, give erlotinib at least 10 hours after the evening dose and at least 2 hours before the next dose.
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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