Nickel (Ni)-induced allergic contact dermatitis (ACD) was performed in human volunteers to study the role of moisturisers in preventing ACD-related skin barrier damage. 15 Ni-sensitive females (mean age: 29.5 years; range: 23-38) were included. On days 1, 21, 24 and 26, TEWL, stratum corneum (SC)-capacitance and clinical score were evaluated on four test sites on the right and left forearms. Both a highly and a poorly hydrating moisturising formulation were applied on two sites from days 1 to 21, after which Ni-ACD was induced on the 2 pre-treated sites and one non-treated area. On day 24, TEWL values were significantly increased on the site pre-treated with poorly hydrating product compared to the rich formulation pre-treated site. SC-hydration was significantly improved on the latter site on days 21, 23 and 26. Long-term use of inadequate moisturiser increases skin barrier damage due to Ni-ACD.