While there are EU laws for priority allergenic ingredients information on food product packaging, there is no legislation about Precautionary Allergen Labelling (PAL) for unintended allergen presence (UAP). As a result, PAL is used in different ways by different manufacturers and retailers, which hampers consumers’ interpretation of the information in the PAL. Previous research has focused on the forms of PAL that are used and on the way they are interpreted and used by consumers. This study adds the perspective of producers, retailers and branch organizations. Thirteen interviews with QA- and QC-professionals were conducted to find out more about the reasoning behind their PAL-use and to find out how PAL could be optimized. Results show that harmonization is needed, on different levels: in the way information on UAP is shared between parties involved in the food chain; in the way PAL is presented and phrased; and in the rules and regulations on PAL. More research is needed on possible ways to share (updates on) information on UAP with consumers