Nervous System Home > Trihexyphenidyl

How Does Trihexyphenidyl Work?

Trihexyphenidyl is known as an anticholinergic medication. It works by blocking the effects of acetylcholine, a neurotransmitter (a signaling chemical in the nervous system). Normal muscle movement control requires a precise balance between acetylcholine and dopamine (another neurotransmitter). In Parkinson's disease (and with extrapyramidal symptoms caused by antipsychotic medications), dopamine levels are decreased, creating an imbalance between dopamine and acetylcholine. By blocking the effects of acetylcholine, trihexyphenidyl helps to re-establish a normal balance between the two chemicals.
Although trihexyphenidyl also has antihistamine effects, these are not thought to be important for treating Parkinson's disease or extrapyramidal symptoms.

When and How to Take the Medication

General considerations for when and how to take trihexyphenidyl include the following:
  • The medication comes in tablet and elixir form. It is taken by mouth, usually three or four times daily.
  • Trihexyphenidyl can be taken before or after meals, whichever works best for you. If dry mouth is a problem, try taking your dose before meals. For people with excessive salivation, taking it after meals can be beneficial.
  • Make sure to take trihexyphenidyl at the same times each day to maintain an even level in your blood.
  • For the medication to work properly, it must be taken as prescribed. Trihexyphenidyl will not work if you stop taking it. Do not stop taking it suddenly without first talking to your healthcare provider.

Dosing Information

The dose of trihexyphenidyl your healthcare provider recommends will vary, depending on a number of factors, including:
  • The medical condition being treated
  • How you respond to trihexyphenidyl (especially if you develop side effects)
  • Other medications you are taking
  • Other medical conditions you may have.
As is always the case, do not adjust your dose unless your healthcare provider specifically instructs you to do so.
(Click Trihexyphenidyl Dosage for more information.)
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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