Drug interactions
Diphenhydramine + Pholcodine
Severity: Moderate
Diphenhydramine and Pholcodine: 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
Pholcodine is an opioid antitussive with sedative properties, and when it is taken with diphenhydramine drowsiness and psychomotor impairment may increase. Respiratory depression is uncommon at antitussive doses but possible at high doses or in vulnerable patients.
What this interaction means in plain words
Diphenhydramine and Pholcodine 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.
Why it happens
Additive CNS depression from opioid receptor agonism and H1 antagonism.
What to do
Advise patients to avoid driving and alcohol, and use the lowest effective doses. Monitor for excessive sedation, particularly in children and older adults.
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 Diphenhydramine
Frequently asked questions
Can I take Diphenhydramine with Pholcodine?
MediHelp rates the interaction as moderate. Diphenhydramine and Pholcodine 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. Pholcodine is an opioid antitussive with sedative properties, and when it is taken with diphenhydramine drowsiness and psychomotor impairment may increase. Respiratory depression is uncommon at antitussive doses but possible at high doses or in vulnerable patients.
How serious is the interaction between Diphenhydramine and Pholcodine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Advise patients to avoid driving and alcohol, and use the lowest effective doses. Monitor for excessive sedation, particularly in children and older adults.
What other medicines interact with Diphenhydramine?
MediHelp also lists interactions of Diphenhydramine with, for example, Alfentanil, Belladonna and opium, Benzhydrocodone / acetaminophen. The full list is on the Diphenhydramine page.
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