Background Anaphylaxis is a potentially life-threatening condition caused by a variety of triggers. However, anaphylaxis following an abdominal trauma is an exceptionally rare condition and could be the first and only sign of hepatic hydatid cyst, especially when no obvious etiology is present. Here, we present such a rare case and discuss relevant diagnostic and management strategy in light of the literature. Case report This case report refers to a 17 year-old previously healthy girl admitted in our pediatric emergency department (ED) for syncope after a minor blunt abdominal trauma. She was hypotensive on admission and shortly after she developed urticaria and angioedema. She was diagnosed with anaphylaxis and treated immediately. Possible etiologies including drug or food ingestion, insect bite, and previous allergy/anaphylaxis history were excluded. After stabilization abdominal imaging was performed, which revealed a ruptured large hepatic hydatid cyst in the vicinity of biliary tree. Albendazole treatment was started and surgical resection was performed after clinical stabilization, which confirmed the cyst rupture into the biliary ducts. Patient recovered without complications after surgery and was discharged uneventfully. Conclusion This case report highlights that hydatid cyst rupture should be included in the differential diagnosis of anaphylaxis without obvious etiology, particularly in regions where hydatid disease is endemic. Ruptured hydatid cyst leading to anaphylaxis requires timely diagnosis, management and emergent intervention.