Abstract: Axions and ALPs are among the best motivated extensions of of the Standard Model. In this talk we discuss how ALP parameters at the UV scale relate to those at the lower energies of experiments, and show that regardless the specific UV coupling configuration a plethora of low-energy couplings is generated, including flavour-changing ones. This then allows us to utilise flavour experiments to put strong constraints on ALP parameters, which are comparable with bounds from astrophysics and colliders. Furthermore, we demonstrate that in a common normalisation of the ALP Lagrangian certain two-loop diagrams must be taken into account to obtain a consistent picture.