Prescription under medical supervision

Therapeutic action

– Anticholinergic antiparkinson drug


– Second-line treatment of extrapyramidal reactions induced by antipsychotics

Forms and strengths

– 2 mg tablet


– Adult: 2 mg once daily, then increase if necessary up to 2 mg 2 or 3 times daily (max. 12 mg daily)
– Administer the lowest effective dose in elderly patients and do not exceed 10 mg daily.


– As long as antipsychotic treatment lasts.

Contra-indications, adverse effects, precautions

– Do not administer to patients with closed-angle glaucoma, prostate disorders, gastrointestinal obstruction or atony.
– Administer with caution and carefully monitor use in elderly patients (risk of mental confusion, hallucinations).
– May cause: anticholinergic effects (dry mouth, constipation, blurred vision, tachycardia, disorders of micturition), confusion, hallucinations, memory loss.
– Avoid or monitor combination with other anticholinergic drugs (atropine, amitriptyline, chlorpromazine, promethazine, etc.).
– Pregnancy: re-evaluate whether the antipsychotic treatment is still necessary; if treatment is continued, administer trihexyphenidyl at the lowest effective dose; observe the neonate if the mother was under treatment in the 3rd trimester (risk of anticholinergic effects, e.g. tremors, abdominal distension).
– Breast-feeding: if treatment is necessary, administer at the lowest effective dose and observe the child (risk of anticholinergic effects, e.g. tachycardia, constipation, thickening of bronchial secretions).


– Take with meals.
– Also comes in 2 mg extended-release capsule, administered once daily.
– Trihexyphenidyl is also used in treatment of Parkinson’s disease.
– Storage: below 25 °C -