Drug interactions
Dicyclomine + Diphenhydramine
Severity: Moderate
Dicyclomine and Diphenhydramine: 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 is a first-generation antihistamine with strong anticholinergic effects. Combined with dicyclomine it increases the risk of sedation, confusion, dry mouth, urinary retention, constipation and tachycardia, especially in older adults.
What this interaction means in plain words
Dicyclomine and Diphenhydramine 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.
Dicyclomine belongs to Respiratory; Diphenhydramine belongs to Respiratory.
Why it happens
Additive muscarinic receptor antagonism with additional central sedation.
What to do
Avoid the combination in older adults; in others use the lowest doses and monitor for delirium, urinary retention and constipation.
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 Dicyclomine
- Clozapine + Dicyclomine Major
- Dicyclomine + Henbane Major
- Dicyclomine + Imipramine Major
- Dicyclomine + Pramlintide Major
- Abobotulinumtoxina + Dicyclomine Moderate
- Aclidinium + Dicyclomine Moderate
Other interactions of Diphenhydramine
Frequently asked questions
Can I take Dicyclomine with Diphenhydramine?
MediHelp rates the interaction as moderate. Dicyclomine and Diphenhydramine 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 is a first-generation antihistamine with strong anticholinergic effects. Combined with dicyclomine it increases the risk of sedation, confusion, dry mouth, urinary retention, constipation and tachycardia, especially in older adults.
How serious is the interaction between Dicyclomine and Diphenhydramine?
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 in older adults; in others use the lowest doses and monitor for delirium, urinary retention and constipation.
What other medicines interact with Dicyclomine?
MediHelp also lists interactions of Dicyclomine with, for example, Clozapine, Henbane, Imipramine. The full list is on the Dicyclomine page.
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