Characteristics of nickel-allergic dermatitis patients seen in private dermatology clinics in Denmark: a questionnaire study.

The use of nickel in certain consumer goods has been regulated in Denmark since 1990. The aim of this study was to reveal the clinical characteristics of nickel-allergic patients seen in seven private dermatology clinics and to identify current sources of nickel that may elicit nickel dermatitis. During 2006 to 2007, 634 patients with dermatitis aged 17-91 years were patch-tested and completed a questionnaire including a question about the occurrence of dermatitis following skin contact with ear-rings or ear-pins, watches, buttons or metal clasps (i.