Introduction: Dengue is a significant public health concern in Brazil, characterized by its extensive territorial distribution, seasonal patterns, and regional variations. A substantial increase in reported cases in 2024 placed a critical burden on emergency services. Objective: To describe the number of dengue notifications in Brazil from 2015 to September 2025 by age group and discuss their implications for Emergency Medicine. Methods: This ecological, descriptive, and quantitative study used secondary data from the National Notifiable Diseases Information System (SINAN) via the TABNET/DATASUS platform. All probable dengue notifications (excluding discarded cases) from 2015 to September 2025 were included. Results: A total of 18,231,381 cases were reported between 2015 and 2025, with the highest number occurring in 2024 (6,431,065; 35.3%). The most affected age group was 20–39 years, accounting for 6,592,263 cases (36.2%), while the least affected were individuals aged 80 years or older, at 260,518 (1.43%). Adolescents aged 10–19 years accounted for 2,862,216 cases (15.7%) and have been eligible for free dengue vaccination since 2024. In this group, 970,410 cases were reported in 2024, which represents an approximately 297% increase from the 244,423 cases reported in 2023. As of September 2025, 217,313 cases had been notified in this age group. Conclusion: Dengue notifications increased substantially between 2015 and 2024, with a potential decline in 2025, especially among adolescents. The high concentration of cases among this age group and young adults presents a significant challenge for emergency services, requiring rapid triage, fluid management, and the timely identification of severe cases. Therefore, these fluctuations have a significant impact on the organization of emergency services, underscoring the need for enhanced preparedness, staff training, and effective resource allocation to manage seasonal surges and mitigate morbidity and mortality.