Drug interactions
Cimetidine + Sildenafil
Severity: Moderate
Cimetidine and Sildenafil: 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 increases sildenafil plasma concentrations modestly. This may heighten vasodilatory effects such as headache, flushing and hypotension.
What this interaction means in plain words
Cimetidine and Sildenafil 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; Sildenafil belongs to Genitourinary.
Why it happens
Cimetidine inhibits CYP3A4 and reduces the metabolism of sildenafil.
What to do
Consider starting sildenafil at 25 mg in patients taking cimetidine, as per labeling, and monitor blood pressure and tolerability.
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 Sildenafil
- Amyl nitrite + Sildenafil Contraindicated
- Atazanavir + Sildenafil Contraindicated
- Cobicistat + Sildenafil Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Sildenafil Contraindicated
- Glyceryl trinitrate pr + Sildenafil Contraindicated
- Isosorbide dinitrate + Sildenafil Contraindicated
Frequently asked questions
Can I take Cimetidine with Sildenafil?
MediHelp rates the interaction as moderate. Cimetidine and Sildenafil 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 increases sildenafil plasma concentrations modestly. This may heighten vasodilatory effects such as headache, flushing and hypotension.
How serious is the interaction between Cimetidine and Sildenafil?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Consider starting sildenafil at 25 mg in patients taking cimetidine, as per labeling, and monitor blood pressure and tolerability.
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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