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Abstract

Attention-deficit/hyperactivity disorder (ADHD) is among the most prevalent neurodevelopmental disorders in children. Psychostimulants, particularly methylphenidate, are first-line pharmacological agents with robust evidence of efficacy and a favorable safety profile. However, abrupt offset of pharmacodynamic effect may precipitate a rebound phenomenon, characterized by transient exacerbation of irritability, hyperactivity, and behavioral dysregulation. This phenomenon is rarely documented in scientific literature and likely underdiagnosed.
An eight-year-old boy with unremarkable past medical and family history presented with longstanding inattention, increased motor activity, and academic underachievement. Other comorbid conditions were excluded.
Diagnosis of ADHD was established. Treatment was initiated with extended-release methylphenidate. Daily late-afternoon episodes of marked irritability and increased motor restlessness emerged, consistent with methylphenidate rebound. Add-on administration of immediate-release methylphenidate in the afternoon resulted in effective mitigation of rebound symptoms.
This case study aims to review the semiological characteristics of the rebound effect induced by methylphenidate and the respective therapeutic approach.