Contact sensitivity to chlorhexidine?

In a joint study, 2061 patients (1346 women and 715 men) were patch tested with chlorhexidine gluconate 1% in water, included in a standard test series. 48 patients (2.3%) showed a positive reaction. These were relatively more common in men (3.2%) than in women (1.9%). Positive reactions were most common in patients with leg eczema (6.8%) or leg ulcer (10.9%). Of the 48 patients who were patch test positive, 14 (2 with leg ulcer) were retested with chlorhexidine gluconate 0.01 and 1%. Only one with a leg ulcer was positive. These findings indicate that false positive reactions, known as "the excited skin syndrome", may arise from testing eczema patients in a standard series. The sensitizing potential of chlorhexidine may be very low, but the potential in patients with an eczema or ulcer of the leg has to be further evaluated.