Abstract Background The decline in self-rated health among children and adolescents raises concerns for their overall well-being and future health outcomes. We examined whether self-rated health in preadolescence predicts both psychiatric and somatic prescription redemption and hospital contacts in later adolescence. Methods This cohort study is part of the Danish National Birth Cohort and focuses on children born between 1996 and 2003. A survey was distributed to 96,382 preadolescents aged 11, who were then followed from 2010 to 2018 (average follow-up of 6.9 years). Data on prescriptions and hospital contacts were obtained from Danish registries. Negative binomial regression was employed to calculate the incidence rate ratio (IRR), comparing preadolescent children who rated their health as poor (‘Not So Good’/’Poor’) to those who rated it as good (‘Excellent’/’Good’). Results Of the 47,365 (49.1%) 11-year-old preadolescents who participated in this study, 5.3% reported experiencing poor self-rated health. Overall, adjusted analyses revealed higher rates of prescription redemptions (IRR 1.63 [95% CI: 1.53; 1.73]) and hospital contacts (IRR 1.86 [95% CI: 1.74; 1.99]) in these children. Poor self-rated health in preadolescence was associated with more somatic (IRR 1.51 [95% CI: 1.40; 1.62]) and psychiatric (IRR 3.04 [95% CI: 2.59; 3.57]) prescriptions, as well as somatic (IRR 1.61 [95% CI: 1.51; 1.72]) and psychiatric (IRR 2.80 [95% CI: 2.42; 3.25]) hospital contacts in adolescence, with similar associations across sexes. Conclusions Poor self-rated health in preadolescence is associated with higher rates of prescription redemption and hospital visits in adolescence, suggesting that perceptions of health in early life influence long-term well-being, especially regarding psychiatric health. This straightforward self-rated health measure offers healthcare professionals valuable insights for identifying children who may require support and early intervention. Key messages • Poor self-rated health in preadolescence predicts higher prescription redemption and hospital visits in adolescence, especially regarding psychiatric health. • Simple self-assessment of health in childhood may have the potential to help identify those needing support and early intervention for long-term well-being.