Drug interactions
Bethanechol + Diphenhydramine
Severity: Moderate
Bethanechol 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 has pronounced anticholinergic activity that can weaken bethanechol's muscarinic effects and promote urinary retention.
What this interaction means in plain words
Bethanechol 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.
Bethanechol belongs to Gastrointestinal Tract; Diphenhydramine belongs to Respiratory.
Why it happens
Antimuscarinic action of diphenhydramine opposes bethanechol at muscarinic receptors.
What to do
Monitor bladder emptying and bethanechol response; prefer a non-sedating second-generation antihistamine.
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 Bethanechol
- Bethanechol + Darifenacin Major
- Bethanechol + Fesoterodine Major
- Bethanechol + Oxybutynin Major
- Bethanechol + Physostigmine Major
- Amifampridine + Bethanechol Moderate
- Amitriptyline + Bethanechol Moderate
Other interactions of Diphenhydramine
Frequently asked questions
Can I take Bethanechol with Diphenhydramine?
MediHelp rates the interaction as moderate. Bethanechol 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 has pronounced anticholinergic activity that can weaken bethanechol's muscarinic effects and promote urinary retention.
How serious is the interaction between Bethanechol 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: Monitor bladder emptying and bethanechol response; prefer a non-sedating second-generation antihistamine.
What other medicines interact with Bethanechol?
MediHelp also lists interactions of Bethanechol with, for example, Darifenacin, Fesoterodine, Oxybutynin. The full list is on the Bethanechol page.
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