Abstract
Background: Adolescence is a vulnerable period for the onset of severe psychiatric conditions, such as psychotic spectrum disorders. Non-adherence to antipsychotics is a common problem in young people with these conditions and paves the way for relapse, rehospitalization, and functional impairment. Co-occurring substance use disorders (SUDs) further undermine adherence and worsen outcomes. Long-acting injectable antipsychotics (LAIs) improve adherence and outcomes in adults, but none are licensed for use in individuals under 18. This review seeks to distill the available evidence on LAIs' use in adolescents, from efficacy to safety, and to outline clinical practice recommendations. Methods: A narrative review was conducted. The evidence was organized by drug class: risperidone, paliperidone, aripiprazole, and other antipsychotics (olanzapine, haloperidol, first-generation depots). Results: Evidence in adolescents remains sparse and heterogeneous. Risperidone LAI has shown improvements in symptom severity, functioning, and behavioral control in bipolar disorder and schizophrenia, though commonly associated with side effects. Paliperidone palmitate demonstrated benefit in first-episode schizophrenia and autism spectrum disorder with intellectual disability, reducing hospital use but carrying risks of EPS and hyperprolactinemia. Aripiprazole LAI showed functional gains, short-term tolerability, and encouraging acceptance in case reports. Other LAIs were used in highly resistant cases with some clinical benefit, though extrapyramidal adverse events were common. Conclusions: The current literature provides limited data, and no clinical guidelines exist for the use of LAI in adolescents. Nonetheless, off-label use is reported in selected cases in clinical practice. Best practice is to start with oral stabilization, then use the lowest effective LAI with psychosocial support and close monitoring. When SUD co-occurs, LAIs may also help mitigate risks related to misuse/diversion of oral medication, provided that care includes systematic SUD screening and early intervention. Prospective controlled studies are urgently needed to establish long-term efficacy and safety in this vulnerable population.