Background – While the definition of anaphylaxis is clear, its grade of severity remains a subject of debate, especially since different published classifications provide different grading score, and the same reaction may not receive the same score from different classifications. The objective of this study was to evaluate the possible discrepancies in severity scoring system for anaphylaxis in patients with a positive food challenge (OFC), using the WHO for the 11 th version of the International Classification of Diseases (ICD-11) as the main reference. Methods – We conducted a retrospective observational study at the University Hospital of Montpellier, France, including patients with a positive OFC, between 2018 and 2022. We classified the severity of each reaction, as per the ICD-11 classification, but also as per four other widely used and validated classifications for grading anaphylaxis severity. Results – 235 patients presented a positive OFC between January 2018 and December 2022: 143 suffered from anaphylaxis, according to the ICD-11 classification. 76.2% of them were classified as grade 2 according to the ICD-11 classification, and 23.8% as grade 3. When comparing the different classifications, a complete concordance was recorded in 8 patients (5.6%) only. All classifications showed a good sensitivity (ranging from 99.3 to 100%), but different specificity (from 67.4 to 93.5%), and discrepancies between them were shown in most patients. Conclusion – Our work highlights the need to refine the different scoring systems, to accurately capture anaphylactic reactions and ensure appropriate management, and, in the end, to adopt a universal, intuitive, and easy-to-use classification, such as the ICD-11 one.