Secondary food allergies due to cross-reactivity between pollen and plant food allergens are a significant and increasingly global health issue. The term 'pollen-food allergy syndrome' (PEAS) defines a series of clinical symptoms in pollen-sensitised patients after the ingestion of plant-derived food. The symptoms of PEAS range from localised oral symptoms to severe systemic reactions. The exact prevalence of PEAS is uncertain for various reasons, including a wide geographical distribution and the lack of standardised population-based studies. Three highly conserved protein classes responsible for most PFAS cases are the profilin, the pathogenesis-related protein group 10 (PR-10) and non-specific lipid transfer proteins (nsLTPs). It has been postulated that climate change, pollution and agricultural practices may increase the expression of these and other defence proteins in plants, causing an increase in allergen load exposure. With advances in component-resolved diagnostic testing, the role of these other allergens can now be revealed. The diagnosis of PFAS is multifaceted and includes a comprehensive clinical history focusing on inhalant allergy and potential cross-reactivities combined with different in vitro and in vivo tests. A better understanding of the cross-reacting allergens and their characteristics may create an awareness of this allergy syndrome essential to managing such patients correctly.