Gold allergy in Japan.

In Japan, gold dermatitis due to ear piercing increased in the early 1990s, but has subsequently become rare. To evaluate this clinical finding and to determine the frequency of gold allergy in Japan, we analysed the results of patch testing with 0.2% gold chloride from 1990 to 2001. 653 patients were tested from March 1990 to December 2001. 55 patients showed a positive reaction to gold (8.4%). Significantly more women (10.2%) than men (0.8%) reacted (P < 0.005), but there was no significant difference between positive rates from 1990 to 1995 (9.2%) and from 1996 to 2001 (7.2%). Our data suggest that patients with gold allergy did not decrease in number, despite a decreased number of patients showing clinically overt gold dermatitis. Thus, gold allergy has changed from being clinically overt to becoming occult in Japan.