Drug interactions
Cimetidine + Tolvaptan
Severity: Moderate
Cimetidine and Tolvaptan: 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 is a weak to moderate CYP3A inhibitor and may raise tolvaptan exposure. Higher tolvaptan levels can cause excessive aquaresis, thirst, dehydration and too rapid a rise in serum sodium.
What this interaction means in plain words
Cimetidine and Tolvaptan 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; Tolvaptan belongs to Endocrine.
Why it happens
Inhibition of CYP3A4-mediated metabolism of tolvaptan by cimetidine.
What to do
Monitor serum sodium, fluid status and urine output closely, and reduce the tolvaptan dose if excessive aquaresis occurs. Consider an H2 blocker without CYP inhibition, such as famotidine.
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 Tolvaptan
- Atazanavir + Tolvaptan Contraindicated
- Ceritinib + Tolvaptan Contraindicated
- Cobicistat + Tolvaptan Contraindicated
- Conivaptan + Tolvaptan Contraindicated
- Darunavir + Tolvaptan Contraindicated
- Idelalisib + Tolvaptan Contraindicated
Frequently asked questions
Can I take Cimetidine with Tolvaptan?
MediHelp rates the interaction as moderate. Cimetidine and Tolvaptan 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 is a weak to moderate CYP3A inhibitor and may raise tolvaptan exposure. Higher tolvaptan levels can cause excessive aquaresis, thirst, dehydration and too rapid a rise in serum sodium.
How serious is the interaction between Cimetidine and Tolvaptan?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor serum sodium, fluid status and urine output closely, and reduce the tolvaptan dose if excessive aquaresis occurs. Consider an H2 blocker without CYP inhibition, such as famotidine.
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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