Background As extract‐based skin testing as well as in vitro tests for major allergens have their own advantages, both procedures are usually performed in routine settings. In times of shortages in medical staff and supplies, we asked ourselves, how many patients would be underdiagnosed, if only one test could be used. Methods In a retrospective analysis, we investigated a cohort of 2646 patients seen by a single physician in a large Austrian outpatient allergy clinic in 2018. Only patients with an allergen source‐specific history and pairs of extract‐based skin prick (SPT) and in vitro molecular allergy tests to major allergens were included. Results For all tested allergen sources, sensitivity was higher for SPT than for sIgE‐based molecular allergy testing. Concerning 1006 birch pollen‐allergic patients, 791 (78.6%) had positive results with both tests, while 153 (15.2%) only with the SPT and 62 (6.2%) only with the sIgE to Bet v1. The other allergen sources showed similar results: For house dust mite 816/1120 (72.9%), grass pollen 1077/1416 (76.1%) and cat 433/622 (69.6%) remained test‐positive with both procedures, whereas in 276 (24.6%), 224 (15.8%) and 173 (27.8%) times only the SPT and 28 (2.5%), 115 (8.1%) and 16 (2.6%) times only the sIgE to Der p1/2/23, Phl p1/5 and Fel d1 showed a positive result. Each comparison was statistically significant (each p < 0.0001, Chi‐squared test). Conclusions Screening for allergy with major molecular allergens has lower sensitivity when compared with extract‐based skin tests. A combination of both is required for an optimal sensitivity.

Summary Background Among allergists, it is often assumed that allergies primarily affect children and young adults and are “lost” during life. Methods To challenge this assumption, we analysed skin prick tests and patch tests from a large patient cohort of 5857 consecutive patients seen by the same physician in 2018 in a large allergy outpatient clinic in Vienna. Results We observed a clustering of patients suffering from inhalant allergy between the ages of 5 and 59 years (44.6% = 2155/4828), although inhalant allergies were still frequent beyond the age of 60 years with 20.2% (167/826). Food allergies were most relevant in infants under 5 years of age, at 16.3% (33/203). The proportion of contact allergies was low in childhood, but steadily increased over the age and affected more often women (women: 5.28% = 187/3544, men: 1.99% = 46/2313). Conclusion Inhalant allergies play a relevant role until old age. Food allergies are mainly a disease of infancy, and contact allergies predominantly affect adult women.

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