Drug interactions
Oxybutynin + Trihexyphenidyl
Severity: Major
Oxybutynin 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 are potent anticholinergics, so together they can cause marked dry mouth, constipation, urinary retention, blurred vision, tachycardia, confusion and hallucinations. Elderly patients are at high risk of delirium and ileus.
What this interaction means in plain words
Oxybutynin 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.
Oxybutynin belongs to Genitourinary; Trihexyphenidyl belongs to Central Nervous System.
Why it happens
Additive muscarinic receptor antagonism.
What to do
Avoid the combination where possible, using a non-anticholinergic bladder agent. If used, monitor for delirium, constipation and urinary retention and use the lowest doses.
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 Oxybutynin
- Bethanechol + Oxybutynin Major
- Clozapine + Oxybutynin Major
- Oxybutynin + Potassium chloride Major
- Oxybutynin + Rivastigmine Major
- Abobotulinumtoxina + Oxybutynin Moderate
- Aclidinium + Oxybutynin Moderate
Other interactions of Trihexyphenidyl
Frequently asked questions
Can I take Oxybutynin with Trihexyphenidyl?
MediHelp rates the interaction as major. Oxybutynin 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 are potent anticholinergics, so together they can cause marked dry mouth, constipation, urinary retention, blurred vision, tachycardia, confusion and hallucinations. Elderly patients are at high risk of delirium and ileus.
How serious is the interaction between Oxybutynin 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, using a non-anticholinergic bladder agent. If used, monitor for delirium, constipation and urinary retention and use the lowest doses.
What other medicines interact with Oxybutynin?
MediHelp also lists interactions of Oxybutynin with, for example, Bethanechol, Clozapine, Potassium chloride. The full list is on the Oxybutynin page.
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