Drug interactions
Solifenacin + Trihexyphenidyl
Severity: Major
Solifenacin and Trihexyphenidyl: major 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
Both drugs are antimuscarinic, so combined use can produce marked dry mouth, constipation, urinary retention, blurred vision, tachycardia and confusion. Older adults are especially vulnerable to cognitive impairment and delirium.
What this interaction means in plain words
Solifenacin and Trihexyphenidyl can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Solifenacin belongs to Genitourinary; Trihexyphenidyl belongs to Central Nervous System.
Why it happens
Additive antagonism of muscarinic receptors.
What to do
Avoid the combination where possible, particularly in older adults. If necessary, use the lowest effective doses and monitor for urinary retention, constipation and cognitive changes.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Solifenacin
Other interactions of Trihexyphenidyl
Frequently asked questions
Can I take Solifenacin with Trihexyphenidyl?
MediHelp rates the interaction as major. Solifenacin and Trihexyphenidyl can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both drugs are antimuscarinic, so combined use can produce marked dry mouth, constipation, urinary retention, blurred vision, tachycardia and confusion. Older adults are especially vulnerable to cognitive impairment and delirium.
How serious is the interaction between Solifenacin and Trihexyphenidyl?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination where possible, particularly in older adults. If necessary, use the lowest effective doses and monitor for urinary retention, constipation and cognitive changes.
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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