There is an important knowledge gap in food allergy management in understanding the factors that determine allergic reactions to food, in gathering objective reports of reactions in real time, and in accessing patients' reaction-histories during consultations. We investigate how eHealth methods can close this knowledge gap. We report experiences with an online tool for reporting allergic reactions that we have developed as a web application. This application has been successfully validated by participants from Ireland and the UK, and is currently being used in a pilot where participants report allergic reactions in near-real time.