Advanced psychiatric treatments remain uncertain in preventing suicide among adolescents. Across the 21 Swedish regions, using nationwide registers between 2016-2020, we found negative correlation between adolescent excess suicide mortality (AESM) and regional frequencies of clozapine, ECT, and lithium (CEL) usage among adolescents (β = -0.613, p = 0.0003, 95% CI: -0.338, -0.889) and males (β = -0.404, p = 0.009, 95% CI: -0.130, -0.678). No correlation was found among females (p = 0.197). Highest CEL usage among male adolescents was seen in regions with lowest quartile (Q1) AESM (W = 74, p = 0.012). Regional CEL treatment frequency in 15-19-year-olds was related to lower AESM in males, reflecting potential treatment efficacy, treatment compliance or better-quality mental health care. Suicide prevention may benefit from early recognition and CEL treatment for severe mental illness in male adolescents. The results indicate association but further research, using independent samples and both prospective and observational methodologies, is needed to confirm causality.