Quetiapine is a low-affinity dopamine D2 receptor antagonist, approved for the treatment of bipolar disorder and schizophrenia in children and adolescents by the Food and Drug Administration, but not by European Medicine Agency. Although knowledge of adverse drug reactions in children and adolescents is scarce, quetiapine is increasingly being used for youth in Denmark. The aim of this case study is to discuss adverse drug events (ADEs) spontaneously reported to the Danish Medicines Agency on quetiapine used in the pediatric population in relation to adversive drug reactions (ADRs) reported in the European Summary of Product Characteristics (SPCs). The ADE report database at Danish Medicines Agency was searched for all quetiapine ADRs involving individuals (<18 years) in the period 1997–2015. Fifteen ADE case reports were retrieved, scrutinized, and categorized. The average age was 14.8 years (range 10–17 years) and six patients were boys. The main reported ADEs were (i) endocrine, for example, hyperprolactinemia and hyperthyroidism, (ii) cardiac, for example, tachycardia and QT prolongation, (iii) neurological, for example, seizures and cerebral hemorrhage, and (iv) psychiatric, for example, hallucinations. As some of the reported ADEs are life threatening and not listed as ADRs in the SPCs, off-label use of quetiapine in children and adolescents gives rise to safety concerns.