Nervous System Home > Side Effects of Trihexyphenidyl

Blurred vision, mild nervousness, and dry mouth are some of the common side effects of trihexyphenidyl. Up to 30 to 50 percent of people who take the medication develop side effects, but these side effects are often minor and generally improve over time. However, there are also some rare but potentially serious trihexyphenidyl side effects that require immediate medical attention, including heatstroke, confusion, and hallucinations.

An Introduction to Trihexyphenidyl Side Effects

As with any medicine, trihexyphenidyl hydrochloride (Artane®) may cause side effects. If side effects do occur, they are often minor and either require no treatment or can easily be treated by you or your healthcare provider.
(This article covers many, but not all, of the possible side effects with trihexyphenidyl. Your healthcare provider can discuss a more complete list of trihexyphenidyl side effects with you.)

Serious Side Effects Seen With Trihexyphenidyl

Some side effects with trihexyphenidyl are potentially serious and should be reported immediately to your healthcare provider. Although most of these serious side effects are rare, a few may be common. These serious side effects of trihexyphenidyl include, but are not limited to:
  • Confusion
  • Agitation
  • Glaucoma (an eye condition)
  • Hallucinations
  • Fever, heatstroke, or decreased sweating
  • Severe constipation (which may be a sign of an intestinal blockage)
  • A rapid heart rate (tachycardia)
  • Difficulty passing urine
  • Feeling the need to take trihexyphenidyl more often or at higher doses than prescribed, especially to achieve euphoric feelings
  • Signs of an allergic reaction, including:


    • An unexplained rash
    • Hives
    • Itching
    • Swelling of the mouth or throat
    • Wheezing
    • Difficulty breathing.
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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