Drug interactions
Diphenhydramine + Solifenacin
Severity: Moderate
Diphenhydramine and Solifenacin: 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 strongly anticholinergic antihistamine. Combined with solifenacin it increases the risk of dry mouth, constipation, urinary retention, blurred vision, sedation and confusion, especially in older patients.
What this interaction means in plain words
Diphenhydramine and Solifenacin 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; Solifenacin belongs to Genitourinary.
Why it happens
Additive peripheral and central muscarinic receptor antagonism.
What to do
Avoid regular use of sedating antihistamines with solifenacin, particularly in the elderly. Use a non-sedating antihistamine if needed and monitor for retention and confusion.
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 Solifenacin
Other interactions of Diphenhydramine
Frequently asked questions
Can I take Diphenhydramine with Solifenacin?
MediHelp rates the interaction as moderate. Diphenhydramine and Solifenacin 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 strongly anticholinergic antihistamine. Combined with solifenacin it increases the risk of dry mouth, constipation, urinary retention, blurred vision, sedation and confusion, especially in older patients.
How serious is the interaction between Diphenhydramine and Solifenacin?
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 regular use of sedating antihistamines with solifenacin, particularly in the elderly. Use a non-sedating antihistamine if needed and monitor for retention and confusion.
What other medicines interact with Solifenacin?
MediHelp also lists interactions of Solifenacin with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Solifenacin page.
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