Drug interactions
Levodopa + Trihexyphenidyl
Severity: Minor
Levodopa and Trihexyphenidyl: minor 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
Trihexyphenidyl is often used with levodopa for tremor and may add to motor benefit. It can worsen dyskinesia, and at high doses its slowing of gastric emptying may reduce levodopa absorption, and it adds to anticholinergic burden.
What this interaction means in plain words
Levodopa and Trihexyphenidyl have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Levodopa belongs to Central Nervous System; Trihexyphenidyl belongs to Central Nervous System.
Why it happens
Complementary pharmacodynamic effects, with anticholinergic delay of gastric emptying possibly lowering levodopa absorption.
What to do
Monitor motor response, dyskinesia and cognition, and use the lowest effective trihexyphenidyl dose. Be cautious in older patients because of confusion and urinary retention.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Trihexyphenidyl
Other interactions of Levodopa
- Isocarboxazid + Levodopa Contraindicated
- Levodopa + Phenelzine Contraindicated
- Levodopa + Phenelzine (nonselective MAOI) Contraindicated
- Levodopa + Procarbazine Contraindicated
- Levodopa + Tranylcypromine Contraindicated
- Amisulpride + Levodopa Major
Frequently asked questions
Can I take Levodopa with Trihexyphenidyl?
MediHelp rates the interaction as minor. Levodopa and Trihexyphenidyl have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Trihexyphenidyl is often used with levodopa for tremor and may add to motor benefit. It can worsen dyskinesia, and at high doses its slowing of gastric emptying may reduce levodopa absorption, and it adds to anticholinergic burden.
How serious is the interaction between Levodopa and Trihexyphenidyl?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor motor response, dyskinesia and cognition, and use the lowest effective trihexyphenidyl dose. Be cautious in older patients because of confusion and urinary retention.
What other medicines interact with Trihexyphenidyl?
MediHelp also lists interactions of Trihexyphenidyl with, for example, Orphenadrin, Oxybutynin, Scopolamine. The full list is on the Trihexyphenidyl page.
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