Anaphylaxis can have clinical manifestations that are amplified by factors within and without the patient. They may affect one third of adults, but are less common in children. Data from the Réseau d'Allergo-Vigilance® (RAV) allow the identification of anaphylaxis COFs through the various reports. The aim of our article was to analyse COFs and secondarily comorbidities in patients with a history of moderate to severe anaphylactic reactions (grade ≥2 according to Ring and Messmer). We therefore analysed from this angle all reports of anaphylaxis for food, hymenoptera venom, drugs (in the per-anaesthesia period and independently of the surgical procedure) received by the RAV over the period from 1 January 2016 to 31 December 2020. Results: Patients aged 18-90 years accounted for most of the anaphylaxis cases with cofactors in the analysed register (70 children and 196 adults/792 reports in total). Anaphylaxis was more frequent in males than in females for all causes. In total, atopy was the second most frequent comorbidity in the analysed group. The cofactors and comorbidities were age dependent. Of the 607 patients with food anaphylaxis, 207 (34%) had associated cofactors, of which 70 were children and 137 adults. In the 2 to 18 year old group, the most common cofactors were effort, exposure to temperature extremes, stress, fatigue, pollen peaks, and concomitant medication. The COFs frequently associated in adulthood were effort, concomitant medication, alcohol, exposure to temperature extremes, pollen peaks, stress, fatigue. When analysing the coexistence of 1 or more (maximum 4) COFs in the group > 18 years, it was observed that in most reports (35%) only one COF was notified. Concerning hymenoptera anaphylaxis, among the 56 anaphylaxis cases, COFs were reported in one third of adult patients with a predominance of males. There were 129 cases of drug allergy and of these 38 (30%) had associated COFs. Consideration of COFs is essential for the proper management of patients in allergology because of the risk of future anaphylactic reactions. Following this analysis, we recommend a systematic algorithm for the collection of COFs as well as the measurement (at the time of the incident and at a distance) of tryptase independently of the allergen. These data are crucial to characterise the phenotypes at risk of severe anaphylaxis and thus develop optimal prevention and treatment strategies.