Fig. 1. Duration of hair dye use, frequency of hair dye use, P-phenylenediamine (PPD) positivity and combined dermatologic problems. Exposure time to hair dye (duration [years]×frequency [number of applications/year]) and extent of hair dye contact allergy involvement (direct; mean=60.0 and indirect; mean=130.0) showed a statistically significant correlation (p=0.001). Regarding exposure time to hair dye and PPD positivity (weakly positive, mean=116.83; strongly/extremely positive, mean=127.64), no statistically significant relationship was found (p=0.27). Exposure time to hair dye and the presence of combined dermatologic problems (no, mean=128.7; yes, mean=117.4) did not show a statistically significant correlation (p=0.30). HDCA: hair dye contact allergy.