Comparison of Formulation and Allergenic Potential of Clean and Traditional Shampoos

The study compared the ingredients of 85 "clean" and 124 traditional shampoos to determine their formulations and allergenic potential. It found that "clean" shampoos were less likely to use allergenic chemicals such as methylisothiazolinone (1% vs 36%), methylchloroisothiazolinone (1% vs 32%), and iodopropynyl butylcarbamate (0% vs 9%). However, they used fragrance as often as traditional shampoos, with 100% of "clean" shampoos containing fragrance, which can be irritating or allergenic. None of the "clean" products used parabens, a safe and effective preservative that has faced public skepticism. The study concluded that while "clean" shampoos are less likely to use allergenic and controversial preservatives, the differences in formulation alone cannot predict if they are more or less likely to cause irritant or allergic contact dermatitis in real-world settings.