Resorcinol is commonly used in permanent hair dye formulations and also in acne treatment skincare products. The European Scientific Committee on Consumer Safety has classified it as a strong sensitizer, meaning that it may cause an allergic reaction after repeated use. Both animal studies and case-reports involving humans have shown that resorcinol may disrupt thyroid hormone synthesis and produce goitrogenic effects.
Retinyl Palmitate / Retinol
Retinyl Palmitate/Retinol (Additional Names: Retinoid, Retinoic Acid)
Are forms of vitamin A. While it might be a good ingredient to have in your night cream, it is not recommended to use during the day when exposed to the sun. Animal studies have shown that retinyl palmitate speeds up the photo-carcinogenic effects of the sun and the development of skin tumors and lesions.