Drug interactions
Dimenhydrinate + Trospium
Severity: Moderate
Dimenhydrinate and Trospium: 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
Dimenhydrinate (diphenhydramine) has strong antimuscarinic activity and trospium is an antimuscarinic. Together they may cause more dry mouth, constipation, urinary retention and blurred vision, and trospium has less central effect but diphenhydramine can still cause confusion.
What this interaction means in plain words
Dimenhydrinate and Trospium 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.
Dimenhydrinate belongs to Respiratory; Trospium belongs to Genitourinary.
Why it happens
Additive antimuscarinic pharmacodynamic effects.
What to do
Avoid in older patients and those with urinary retention or constipation; use a non-anticholinergic antiemetic where possible and monitor for anticholinergic effects.
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 Trospium
- Clozapine + Trospium Major
- Pramlintide + Trospium Major
- Thioridazine + Trospium Major
- Trihexyphenidyl + Trospium Major
- Aclidinium + Trospium Moderate
- Amantadine + Trospium Moderate
Other interactions of Dimenhydrinate
Frequently asked questions
Can I take Dimenhydrinate with Trospium?
MediHelp rates the interaction as moderate. Dimenhydrinate and Trospium 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. Dimenhydrinate (diphenhydramine) has strong antimuscarinic activity and trospium is an antimuscarinic. Together they may cause more dry mouth, constipation, urinary retention and blurred vision, and trospium has less central effect but diphenhydramine can still cause confusion.
How serious is the interaction between Dimenhydrinate and Trospium?
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 in older patients and those with urinary retention or constipation; use a non-anticholinergic antiemetic where possible and monitor for anticholinergic effects.
What other medicines interact with Trospium?
MediHelp also lists interactions of Trospium with, for example, Clozapine, Pramlintide, Thioridazine. The full list is on the Trospium page.
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