Demographic, temporal, and clinical factors of anaphylaxis in an urban emergency department: a retrospective analysis

Abstract Purpose Allergic reactions and anaphylaxis are common reasons for emergency department (ED) presentation, yet data on their severity, triggers, and clinical course in German EDs remain limited. This study assessed the epidemiology, characteristics, management, and outcomes of patients presenting with allergic reactions or anaphylaxis to a large urban tertiary ED in Germany. Methods We conducted a retrospective observational study including all patients presenting with a primary diagnosis of allergic reaction or anaphylaxis to the Emergency Department of LMU Hospital Munich (Downtown Campus) between 1 January and 31 December 2023. Demographic data, presentation characteristics, triage acuity, anaphylaxis severity (Ring and Messmer classification), suspected triggers, and clinical outcomes were extracted from electronic health records and analyzed descriptively. Results A total of 277 presentations were identified, representing 1.07% of all 25,898 ED presentations during the study period. Patients were predominantly young adults, with a nearly equal sex distribution. Most reactions were mild (Grade I, 58.1%) or moderate (Grade II, 36.1%), whereas severe reactions (Grade III) occurred in 5.8% of cases; no Grade IV cases were observed. Medications (34.1%), foods (32.7%), and insect stings (21.0%) were the leading triggers. More than half of patients presented within 1 h of symptom onset; greater severity was associated with earlier presentation and shorter waiting times. Complications or recurrent/biphasic symptoms were rare (2.2%). Most patients (96.0%) were discharged after ED treatment, while 3.3% required ward admission and 0.7% intensive care. Conclusion Allergic reactions and anaphylaxis accounted for approximately 1.1% of all ED presentations and were predominantly mild to moderate. Most patients were discharged after ED treatment. These findings provide real-world insight into anaphylaxis epidemiology and emergency care in Germany, underscoring the importance of structured triage, guideline-based management, and early treatment.