Study Links Anaphylaxis Reactions to Suspected Cofactors
Analysis of 16,915 European registry cases finds suspected cofactors in nearly half of reactions, with patterns differing between children and adults.
Updated on Nov. 7, 2026 in Allergies
A study published October 23, 2026 in Clinical and Experimental Allergy analyzed 16,915 anaphylaxis cases recorded in the European Anaphylaxis Registry between 2007 and 2024. Suspected cofactors were documented in 49% of cases.
Why it matters
The findings suggest that circumstances accompanying an allergic exposure, such as medication, exercise or infection, may influence how severe a reaction becomes. Understanding these factors may help clinicians and patients identify situations that warrant extra caution.
Suspected cofactors were documented in 59% of adult cases and 26% of cases in patients under 18, based on registry records. Because the data are observational, the study cannot confirm that these circumstances caused the reactions.
The players
European Anaphylaxis Registry
A multinational registry collecting case records of severe allergic reactions across Europe, providing the dataset used in this analysis.
The details
Researchers assessed reaction severity using the number of organ systems affected and two established classification systems, the Ring and Messmer and Brown scales. Among food-induced reactions, acute infections in children and alcohol consumption in adults were consistently associated with greater severity, and suspected cofactors were linked to longer intervals between exposure and symptom onset.
Timeline
2007 to 2024: Period during which the analyzed registry cases were recorded.
October 23, 2026: Study published online in Clinical and Experimental Allergy.
Health Landscape
The analysis draws on the European Anaphylaxis Registry, a long-running surveillance database covering cases from 2007 through 2024. It shifts attention from the allergen alone toward the circumstances surrounding each reaction.
People with known allergies may want to discuss with their clinicians whether exercise, medication, alcohol or infection could increase their risk during an exposure. Recognizing these accompanying circumstances may inform how carefully someone manages an allergen-containing meal or activity.
The takeaway
Severe allergic reactions often involve more than the allergen itself, and factors such as exercise, medication or illness may matter. Discussing these circumstances with a clinician can help people plan safer routines around known triggers.
Further reading
For more on the conditions behind severe reactions, see Allergies.
Source note: This article includes information reported by European Medical Journal.
