In clinical practice, adverse drug reactions, or ADRs, pose a significant obstacle, particularly for vulnerable populations like children and the elderly. These groups are highly susceptible due to physiological differences, polypharmacy, and altered pharmacokinetics and pharmacodynamics. In tertiary care hospitals, the purpose of this review is to investigate the incidence, patterns, risk factors, and outcomes of ADRs in geriatric and pediatric patients. Multiple studies' findings indicate that ADRs significantly increase hospital admissions and morbidity. In geriatric patients, polypharmacy, comorbidities, and age-related physiological changes increase ADR risk, whereas in pediatric patients, immature organ systems and dosing errors are key contributors. Various assessment tools such as the Naranjo Scale and Hartwig Severity Scale are widely used to evaluate ADRs. Pharmacovigilance programs play a crucial role in monitoring and preventing ADRs. The review highlights the need for improved ADR reporting systems, rational prescribing, and patient-specific therapeutic approaches to minimize adverse outcomes.