Utilising smart-phone applications to gather data is an expanding field in medicine. However, it is not without limitations including bias. The European Innovation Partnership on Active and Healthy Ageing (EIP on AHA) introduced the Allergy Diary application as part of its Action Plan MASK-rhinitis (MACVIA-ARIA Sentinel Network for allergic rhinitis). The aim of the app is to collect a daily recording of allergic rhinitis control. Authors in this pilot study analysed the data provided by the app users in response to eight questions about their nasal symptoms, effects on their quality of life, medications used, presence of asthma and specific allergies that they might have. Authors used the number of symptoms (including ocular) to classify the severity of rhinitis. Data were collected from 3260 users in 20 countries. It was found that nasal obstruction and ocular symptoms have more significant effect on work and quality of life than other symptoms. It was also found that immune therapy correlated with a reduction of occurrence of nasal symptoms. Such correlation was not found in pharmacotherapy. Authors identified potential confounding factors in their study such as measurement and selection bias. They concluded that app technology offers a different type of data to that offered by classical questionnaires and can lead to and answer a different spectrum of research questions.