Objective: Antipsychotic-related prolactin changes may expose children and adolescents to severe adverse reactions (ARs) related to pubertal development and growth. We therefore aimed to assess the effects of antipsychotics on prolactin levels and associated somatic ARs in children and adolescents. Methods: We systematically searched PubMed and CENTRAL for placebo-controlled randomized trials of antipsychotics in children and adolescents aged £18 years, reporting prolactin levels and related ARs. We conducted a random-effect meta-analysis and assessed risk of bias version 2 (ROB2). Results: Thirty-two randomized controlled trials with an average trial duration of 6 weeks, covering 4643 participants with an average age of 13 years and a male majority of 65.3%. Risk of bias across domains was low or unclear. The following antipsychotic compounds: aripiprazole (n = 810), asenapine (n = 506), lurasidone (n = 314), olanzapine (n = 179), paliperidone (n = 149), quetiapine (n = 381), risperidone (n = 609), and ziprasidone (n = 16) were compared with placebo (n = 1658). Compared with placebo, statistically significant higher prolactin increase occurred with risperidone (mean difference [MD] = 28.24 ng/mL), paliperidone (20.98 ng/mL), and olanzapine (11.34 ng/mL). Aripiprazole significantly decreased prolactin (MD = -4.91 ng/mL), whereas quetiapine, lurasidone, and asenapine were not associated with significantly different prolactin levels than placebo. Our results on ziprasidone are based on a single study, making it insufficient to draw strong conclusions. On average, 20.8% of patients treated with antipsychotic developed levels of prolactin that were too high (hyperprolactinemia), whereas only 1.03% of patients reported prolactin-related ARs. Data were highly limited for long-term effects. Conclusions: In children and adolescents, risperidone, paliperidone, and olanzapine are associated with significant prolactin increase, whereas aripiprazole is associated with significant decrease. Despite the significant changes in prolactin level, few ARs were reported. Study protocol on PROSPERO: CRD42018116451.