Background The human immune system is confronted daily with a large, chemically-varied range of potentially sensitising substances. Skin sensitising substances are found, above all, in a plethora of consumer products, e. g. cosmetics, jewellery, earrings, toys, textiles, leather, other everyday commodities and, in some cases, also tattoos. These products may contain sensitisers such as fragrances, preservatives, dyes, or other additives. To provide a greater degree of consumer protection, there is a need for specific legal regulation and risk assessment, which covers each possible human exposure to a sensitising substance or mixture. This review article describes the background and pathway towards the development and implementation of an international legal framework for the classification and labelling of chemicals that contain potentially skin sensitising substances. This includes the implementation of the globally harmonized system of classification and labelling of chemicals (GHS), the classification, labelling and packaging (CLP) regulation, registration, evaluation, authorisation and restriction of chemicals (REACH), and the regulation of cosmetics, among other national laws and regulations. Assessment criteria for classification is derived from a suite of in vitro and in vivo assays, Electronic supplementary material The online version of this article (