Anorexia nervosa is characterised by the fear of gaining weight and a disrupted relationship with food but atypical if the body mass index is within normal limits. Semaglutide is a glucagon-like peptide-1 receptor agonist, indicated in patients with diabetes type 2 and obesity. An adolescent girl was diagnosed with atypical anorexia nervosa. She had a fear of gaining weight, she increased her exercise and decreased her caloric intake. The adolescent was admitted to the paediatric ward with bradycardia and pericardial effusion. During her hospital stay she admitted to having used semaglutide. Semaglutide was prescribed by her general practitioner because she was previously on the verge of being overweight with weight-related dysphoria. After 3 months she stopped using semaglutide, she kept losing weight. The adolescent girl went back to her normal life but after a panic attack caused by gaining 1 kg, she was admitted to an eating disorder ward. Semaglutide can affect mental health in patients who are prone to mental disorders. The importance of restrictively prescribing semaglutide for the right indication with caution and strict follow up is emphasised.