Frequency of headache in emergency department patients with anaphylaxis: A cross-sectional study.

Background: Multiple anaphylaxis mediators have been demonstrated to provoke migraine-like attacks following intravascular infusion, suggesting that anaphylaxis could cause headache; however, headache is rarely noted in anaphylaxis and is not included among diagnostic criteria.

Objective: Our study objectives were to estimate the frequency of headache among prospectively enrolled emergency department (ED) patients with anaphylaxis and assess the association of headache with patient and anaphylaxis characteristics.

Methods: A cross-sectional study of ED patients aged ≥5 years who met anaphylaxis diagnostic criteria from January 8, 2020 to September 9, 2022 was conducted. The primary outcome of interest was headache frequency among patients who met at least one anaphylaxis criterion. We explored the association of headache with patient characteristics and anaphylaxis characteristics.

Results: We included 63 patients with anaphylaxis. In all, 17 (27%, 95% confidence interval [CI] 17%-40%) patients reported the presence of a headache. Female patients had more than a nine times increased odds of having headache (odds ratio [OR] 9.3, 95% CI 1.14-77.1, p = 0.016). Presentation with headache was associated with the presence of dyspnea (OR 5.5, 95% CI 1.56-19.7, p = 0.006).

Conclusion: Headache in anaphylaxis may be more common than previously recognized, especially in females. Larger prospective studies are needed to characterize headache as a marker of neurological involvement in anaphylaxis.