Abstract:
This study aimed to investigate the prevalence of allergens in hair dyes sold in Thailand in the years 20242025. A total of 495 products were categorized into three groups: general hair dyes, products labelled as free of ammonia, parabens, or para-phenylenediamine (PPD), and organic hair dyes. The data was collected from physical retail shops and online platforms. All product ingredient and allergen data were collected using Microsoft Excel and statistical analyses were performed using the chi-square test and one-way ANOVA. The results showed that 94.97% of the general hair dyes contained allergens, while 100% of the labelled and organic products contained allergens. The difference in allergen prevalence between general and labelled products was statistically significant (p < 0.05). The mean allergens were highest for organic products, followed by labelled products and general dyes with significantly different mean allergen counts (p < 0.05). The most commonly detected allergen was propylene glycol, followed by cetearyl alcohol and P-phenylenediamine.