Healthcare use among adolescents after vaccination against SARS-CoV-2 is unknown. In a real-life register-based cohort study (trial NCT04786353), healthcare use was compared among Pfizer-BioNTech BNT162b2 COVID-19 vaccinated and unvaccinated 12-18-year-olds. First-dose-vaccinated (between 1 May and 30 September 2021) adolescents were sex and age matched 1:1 with unvaccinated adolescents. Outcomes were visits to emergency rooms, hospitalization, and visits to general practitioners and specialist practitioners. The prior event rate ratio (PERR) was applied. The study finds that boys had fewer visits to general practitioners (PERR 0.93, 95% confidence interval (CI) 0.89-0.99) after the first vaccine. Up to 56 days after the second dose, vaccinated boys had lower rates of visits to specialist practitioners (0.88, 95% CI 0.79-0.99); after 57-182 days, vaccinated girls and boys had higher rates of visits to emergency rooms (1.22, 95% CI 1.08-1.39; 1.17, 95% CI 1.07-1.31) and to general practitioners (1.17, 95% CI 1.12-1.21; 1.17, 95% CI 1.13-1.22). Furthermore, vaccinated boys had higher rates of visits to specialist practitioners (1.23, 95% CI 1.08-1.39). Estimates were close to one and do not indicate that BNT162b2 leads to a practically meaningful increase in healthcare use among vaccinated adolescents.