Drug interactions
Orphenadrin + Trihexyphenidyl
Severity: Major
Orphenadrin 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 produce excessive anticholinergic effects. Risks include confusion, hallucinations, urinary retention, constipation, hyperthermia and tachycardia.
What this interaction means in plain words
Orphenadrin 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.
Orphenadrin belongs to Musculoskeletal; Trihexyphenidyl belongs to Central Nervous System.
Why it happens
Additive muscarinic receptor antagonism.
What to do
Avoid using both where possible, particularly in older adults. If necessary, use the lowest doses and monitor for anticholinergic toxicity.
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 Orphenadrin
Other interactions of Trihexyphenidyl
Frequently asked questions
Can I take Orphenadrin with Trihexyphenidyl?
MediHelp rates the interaction as major. Orphenadrin 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 produce excessive anticholinergic effects. Risks include confusion, hallucinations, urinary retention, constipation, hyperthermia and tachycardia.
How serious is the interaction between Orphenadrin 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 using both where possible, particularly in older adults. If necessary, use the lowest doses and monitor for anticholinergic toxicity.
What other medicines interact with Orphenadrin?
MediHelp also lists interactions of Orphenadrin with, for example, Alfentanil, Amobarbital, Benzhydrocodone / acetaminophen. The full list is on the Orphenadrin page.
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