Abstract
Attention-deficit/ hyperactivity disorder is one of the most commonly observed pediatric psychiatric disorders in today’s child and adolescent psychiatry clinics. Methylphenidate (MPH), a psychostimulant that acts on the dopaminergic system, is frequently used in treatment. Several studies have been performed concerning hiccups, and although some neurological mechanisms have been described, the pathophysiology is still unclear. However, neurotransmitter changes and hypo-/hyperdopaminergic states are known to lead to hiccups. A 7-year-old boy was brought by his parents to our clinic due to hyperactivity, inability to remain still, frequent boredom, and compulsive talking. ADHD was diagnosed on the basis of DSM-5 diagnostic criteria following psychiatric assessments, and MPH was initiated. Hiccups had developed and persisting 3-4 hours after medication administration. Hiccups had resumed when the drug was administered again, and stopped after 3-4 hours. Resolution in cases of hiccups treated with MPH is probably associated with improvement of a hypodopaminergic state through MPH raising dopamine levels. Additionally, we think that MPH can also trigger hiccups (as in our case) by causing a hyperdopaminergic state. We therefore think that further studies are needed in order to clarify the etiology of hiccups and the relationship with drug interactions.

Key words: Attention-deficit/ hyperactivity disorder, hiccup, methylphenidate, child