Context: Children and adolescents with intellectual disability often have various mental disorders and behaviour problems. Despite the limited evidence on the efficacy and safety of psychotropic medication use to children and adolescents with intellectual disability, clinicians often prescribes psychotropic medications for the management of problem behaviours.
 Objective: We aimed to clarify the psychotropic prescribing practices for children and adolescents with intellectual disability.
 Design: We conducted a 1-year cohort study of patients with intellectual disability aged 3-17 years using a large health insurance claims database in Japan.
 Outcome measures: Psychotropic prescription, prescription duration, polypharmacy, and average dosage.
 Results: Of 2,035 patients, the most prevalently prescribed psychotropic medications were antipsychotics (12.5%), anxiolytics/hypnotics (12.4%), stimulants (4.8%), mood stabilizers (2.4%), and antidepressants (1.8%). The prescription prevalences of anxiolytic/hypnotic and antipsychotics increased with age. Patients aged 6 years or older had around 2-fold higher prescription duration of antipsychotics (median duration of over 300 days per year)than those aged 3 to 5 years. The likelihood of polypharmacy and excessive dosage (defined as chlorpromazine equivalents of >300 mg/day) of antipsychotics increased with age.
 Conclusion: We observed a higher prescription prevalences of anxiolytics/hypnotics and antipsychotics and a longer prescription duration of antipsychotics in the present study than those in previous studies. Our results suggest a need for developing clinical practice guidelines for the management of problem behaviours among children and adolescents with intellectual disability.
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