High Risk of Metabolic Side Effects Among New Paediatric Antipsychotic Users in Sweden—A Register‐Based Study

ABSTRACT Purpose This study aims to assess the risk of metabolic side effects among paediatric new users of antipsychotics in Sweden, focusing on differences between substances and sexes. Methods Children aged 5–17 years, who were new users of antipsychotics between 2014 and 2021, were identified using Swedish national health registers. Cox' models were fitted for children during first treatment with an antipsychotic, excluding those with eating disorders, yielding hazard ratios (HRs) for metabolic side effects with 95% confidence intervals (CIs). Results A total of 5441 children were new users of antipsychotics. Of these, 399 (7.3%; 42% girls) received a new diagnosis or new treatment indicating a metabolic side effect, of which 139 cases during first‐line treatment and without an eating disorder diagnosis. Obesity was the most common metabolic side effect, accounting for 69% of the cases. In girls, significantly increased risks were observed for aripiprazole (HR 3.52, 95% CI 1.58–7.80), olanzapine (HR 6.99, 95% CI 2.34–20.93) and quetiapine (HR 4.87, 95% CI 1.97–12.04), compared with risperidone. Younger girls had higher risks. In boys, a significantly increased risk was found for aripiprazole (HR 2.21, 95% CI 1.37–3.56). Conclusion The overall risk of metabolic side effects is considerable, with higher relative risks in girls, especially younger girls. These findings highlight the need for carefully considered treatment and attentive monitoring when initiating antipsychotics in children.