Drug interactions
Diphenhydramine + Propafenone
Severity: Moderate
Diphenhydramine and Propafenone: 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
Diphenhydramine inhibits CYP2D6 and may increase propafenone concentrations, especially in extensive metabolizers. Higher exposure can intensify conduction slowing, dizziness and other adverse effects. Clinical significance is usually modest with occasional doses.
What this interaction means in plain words
Diphenhydramine and Propafenone 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.
Diphenhydramine belongs to Respiratory; Propafenone belongs to Cardiovascular.
Why it happens
Diphenhydramine inhibits CYP2D6-mediated propafenone metabolism.
What to do
Monitor for bradycardia, dizziness and ECG changes if diphenhydramine is used regularly. Consider a non-inhibiting antihistamine such as loratadine for ongoing use.
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 Propafenone
- Dofetilide + Propafenone Contraindicated
- Dronedarone + Propafenone Contraindicated
- Nilotinib + Propafenone Contraindicated
- Nirmatrelvir / ritonavir + Propafenone Contraindicated
- Nirmatrelvir + Propafenone Contraindicated
- Pimozide + Propafenone Contraindicated
Other interactions of Diphenhydramine
Frequently asked questions
Can I take Diphenhydramine with Propafenone?
MediHelp rates the interaction as moderate. Diphenhydramine and Propafenone 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. Diphenhydramine inhibits CYP2D6 and may increase propafenone concentrations, especially in extensive metabolizers. Higher exposure can intensify conduction slowing, dizziness and other adverse effects. Clinical significance is usually modest with occasional doses.
How serious is the interaction between Diphenhydramine and Propafenone?
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 for bradycardia, dizziness and ECG changes if diphenhydramine is used regularly. Consider a non-inhibiting antihistamine such as loratadine for ongoing use.
What other medicines interact with Propafenone?
MediHelp also lists interactions of Propafenone with, for example, Dofetilide, Dronedarone, Nilotinib. The full list is on the Propafenone page.
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