Objective: There is limited available literature on the incidence of allergic diseases in ED. The objective of this study was to investigate the clinical records of patients admitted to the ED with a suspected allergic reaction. Methods: A 1 year retrospective study was carried out and data were collected from the patients’ computerized medical reports. Results: A total of 324 patients were admitted for an allergic event. Of those, 165 patients (50.9%) were female and their mean age was 55 ± 18.5 years. Diagnoses included: asthma in 100 patients (30.9%); hymenoptera allergy in 78 patients (24.1%); food allergy in 31 patients (9.5%); drug allergy in 25 patients (7.7%); and allergic conjunctivitis in 12 patients (3.7%). No diagnosis was found in the medical records of 78 patients (24.1%). Anaphylactic shock was observed in 12 patients (3.7%) with a diagnosis of food allergy (six cases), drug allergy (three cases) and hymenoptera allergy (three cases). Ninety patients (27.7%) were hospitalized in the following units: 38 in allergy unit (42.2%); 20 in intensive care unit (22.2%); 10 in pulmonary unit (11.1%); eight in the dermatology unit (8.9%); six in the internal medicine unit (6.7%); and eight in other units (8.9%). Overall, 42 patients (12.9%) were evaluated by an allergologist after ED discharge with positive allergy results in 28 cases (66.6%). Conclusions: Acute allergic diseases are not rare in ED, representing 1% of the annual visits in our series. A low rate of allergologist referral was observed. Emergency physicians must work closely with allergologists to ensure a better evaluation, long‐term care and preventive management of patients with allergic diseases admitted to the ED.