Introduction and objective Drugs are a frequent cause of severe anaphylactic reactions. Clinical epidemiology of drug-induced anaphylaxis (DIA) supports the identification of the most frequent eliciting drug groups, risk factors, symptoms and treatment procedures. Our aim was to analyze data to promote better recognition and long-term management of affected individuals. Methods Data from the European Anaphylaxis Registry (2007-2019) with 1,815 cases of drug-induced anaphylaxis were analyzed regarding demographics, elicitors, symptoms, comorbidities, and treatment. Results The most frequent eliciting groups of drugs were analgesics (41.27%) – with non-steroidal anti-inflammatory drugs (NSAIDs) being the most common subgroup (65.42%) – antibiotics (33.17%), local anesthetics (7.38%) and radiocontrast media (5.18%). Adrenaline was used more often in patients with DIA (23.20%) than in anaphylaxis due to other causes (17.82%). The majority of events occurred in female patients (65.34%), although they were admitted to hospital (29.01%) or an intensive care unit (ICU) (9.61%) less often. Skin symptoms were most common (84.02%), while gastrointestinal symptoms were reported less frequently (30.25%). Compared to other anaphylactic reactions in the registry (food/insects) severe reactions occurred significantly more often in DIA (5.62% vs. 1.67%). Hospitalization (31.63%) and ICU admission rates (11.85%) were significantly higher in DIA than anaphylactic reactions to other elicitors (27.58% and 5.45%). Conclusions DIA affects middle aged females more frequently and is more severe in elderly males in the sample observed. Analgesics and antibiotics are the leading causes of DIA. Adrenaline was rarely administered to patients, even though it is recommended by guidelines.

Background: There is controversy whether taking β-blockers or ACE inhibitors (ACEI) is a risk factor for more severe systemic insect sting reactions (SSR) and whether it increases the number or severity of adverse events (AE) during venom immunotherapy (VIT). Methods: In this open, prospective, observational, multicenter trial, we recruited patients with a history of a SSR and indication for VIT. The primary objective of this study was to evaluate whether patients taking β-blockers or ACEI show more systemic AE during VIT compared to patients without such treatment. Results: In total, 1,425 patients were enrolled and VIT was performed in 1,342 patients. Of all patients included, 388 (27.2%) took antihypertensive (AHT) drugs (10.4% took β-blockers, 11.9% ACEI, 5.0% β-blockers and ACEI). Only 5.6% of patients under AHT treatment experienced systemic AE during VIT as compared with 7.4% of patients without these drugs (OR: 0.74, 95% CI: 0.43–1.22, p=0.25). The severity of the initial sting reaction was not affected by the intake of β-blockers or ACEI (OR: 1.14, 95% CI: 0.89–1.46, p=0.29). In total, 210 (17.7%) patients were re-stung during VIT and 191 (91.0%) tolerated the sting without systemic symptoms. Of the 19 patients with VIT treatment failure, 4 took β-blockers, none an ACEI. Conclusions: This trial provides robust evidence that taking β-blockers or ACEI does neither increase the frequency of systemic AE during VIT nor aggravate SSR. Moreover, results suggest that these drugs do not impair effectiveness of VIT. (Funded by Medical University of Graz, Austria; Clinicaltrials.gov number, NCT04269629)