Objective : This study is to exam the amazon user reviews from the topical retinol products to extrapolate some relationship among the consumer self-reported side effect, efficacy and retinol content in the products.
Methods: Twelve topical retinol products of different retinol contents were purchased from Amazon. The retinol content in those products was determined through an HPLC method. The amazon user reviews from each product were searched with four different key words “burn”, “irritation”, “effect”, “wrinkle” separately. The reviews contain the key word were exam carefully to determine whether the review is positive (yes) or negative (no) response to the key word, and the percentage of number of yes to the total number of reviews contain the key word was determined. The correlations among the percentage of yes to skin burn, skin irritation, product effectiveness, and reduce wrinkle to the retinol content of the products was evaluated.
Results: There is a nonlinear correlation between the patient observed skin burn and retinol content, between patient observed irritation and the retinol content, and between patient observed efficacy and retinol content, but no correlation between the patent observed wrinkle reduce and retinol content. There is a linear correlation patient observed irritation and patient observed skin burn.
Conclusions: Consumer reviews suggested retinol products with higher retinol content would show higher skin burning, skin irritation, and higher efficacy, but reach their plateau at 0.3 – 0.5% retinol content level.
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