Fieke M. Rosenberg

1 Introduction Hair dye use is a widespread practice [1]. Our previous cross-sectional study demonstrated that nearly two-thirds of the Dutch general population reported having dyed their hair at some point in their lives [1]. Hair dye users were predominantly female (around 80%) [1-3], and more likely to be middle-aged compared to non-users [1]. Adverse skin reactions to hair dye were frequently experienced, affecting 6.8% of the users [1].

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1 INTRODUCTION Hand eczema (HE) is a heterogeneous inflammatory skin disease confined to the hands.1 It is common in the general population, with a lifetime prevalence of around 15%.2, 3 HE often has a multifactorial and complex aetiology with skin barrier dysfunction and immune dysregulation that can be explained by both exogenous and endogenous factors.1 Exogenous factors include exposure to irritants (water/wet-work, soap, disinfectants and friction)4, 5 and exposure to contact allergens.6...