Objectives: To assess quality of life and outcomes associated with adverse effects (AEs) in pediatric patients receiving pharmacological treatment for attention-deficit/hyperactivity disorder (ADHD) and their parents/caregivers. Methods: An online survey was conducted (10/13/2023-10/20/2023) among parents/caregivers recruited from Dynata's U.S. panel who lived with a pediatric patient (6-17 years) currently treated for ADHD. Patient and parent/caregiver characteristics and outcomes were descriptively reported. Patients were considered to have AEs if they experienced symptoms/complications in the past 30 days that appeared, worsened, or remained unchanged after initiating their latest ADHD treatment. Regression analyses were used to estimate correlations between the number of AEs and key outcomes, including patients' health-related quality of life (HRQoL; based on the Pediatric Quality of Life Inventory) and parents/caregivers' work and activity impairments (based on Work Productivity and Activity Impairment: Caregiver) and mental health (based on Patient Health Questionnaire-4). Results: A total of 401 parents/caregivers from all U.S. regions completed the survey (caregiver median age: 38 years, 58.9% female; patient median age: 11 years; 37.7% female). In the 30 days prior to data collection, 66.8% of patients had AEs (overall mean: 1.2 AEs), with insomnia/sleep disturbances and decreased appetite/weight loss being the most frequently reported (14.2% and 11.7%, respectively). The number of AEs was significantly correlated with reduced patient's HRQoL (including reduced physical, emotional, and school functioning), increased parent/caregiver's work and activity impairment, and a higher likelihood of parents/caregivers having generalized anxiety disorder or major depressive disorder, respectively (all p < 0.001). Conclusions: AEs are common among pediatric patients receiving pharmacological treatment for ADHD and are associated with poorer quality of life and outcomes in pediatric patients and their parents/caregivers. Therapies with better safety profiles may help improve patient's HRQoL and parent/caregiver outcomes.