Contact allergy to hair-colouring products: a cosmetovigilance follow-up study by four companies in Europe from 2014 to 2017.

Background: A previous analysis of undesirable events (UEvs), reported to four major companies following the use of hair-colouring products in Europe, showed that the reporting rates were stable for both oxidative and direct hair-colouring products over the period 2003-2006.

Objectives: In order to verify the impact of risk management measures implemented since 2006, as well as the impact of a new Commission Regulation (No 1223/2009), the same four companies analysed cosmetovigilance data collected over an additional four-year period (2014-2017). The objective was to determine whether there was any time effect, country effect, or product type effect, as well as identify risk factors.