Attention deficit hyperactivity disorder (ADHD), a prevalent neurodevelopmental disorder, is characterized by attention deficit, hyperactivity, and impulsivity. It frequently accompanies psychiatric disorders, such as oppositional-defiant disorder, anxiety, and mood disorders in children. Current studies indicate a rising use of atypical antipsychotics in conjunction with psychostimulants to treat ADHD and co-occurring disorders. However, the combination therapy may heighten the risk of adverse effects due to drug-drug interactions. One of these side effects is acute dystonic reaction (ADR), an extrapyramidal symptom characterized by involuntary muscle contractions, particularly in the head and neck region. In this case report, a 6-year-old male patient with ADHD who was initially treated with risperidone and later started on methylphenidate is presented. After discontinuing methylphenidate, the child developed ADR, involuntary contractions in his face and neck. The abrupt cessation of methylphenidate in combination therapy with risperidone resulted in the occurrence of dystonia as an extrapyramidal system side effect. Symptomatic improvement was observed with the biperiden treatment. Pharmacodynamic interactions between methylphenidate and risperidone, particularly involving dopamine pathways, were implicated in the development of ADR. This case report emphasizes the importance of recognizing and managing potential side effects, such as dystonia, when altering combinations of psychostimulant and antipsychotic medications. It also highlights the need for cautious dose adjustments and gradual tapering of medications to mitigate the risk of movement disorders. Additionally, the case underscores the significance of considering individual risk factors, medical history, and genetic predispositions in treatment decision-making.
