Most of the products offered by Olaplex contain blacklisted ingredients such as phenoxyethanol, fragrance, sodium lauryl sulfoacetate, and iodopropynyl butylcarbamate. The difference between Olaplex and other similar products is that they use Bis-Aminopropyl Diglycol Dimaleate as part of a complex chemical process that is at the heart of Olaplex's patented technology for hair restructuring. While it's not a blacklisted ingredient, there are many attempts to "falsify" these products on the market, and we do recommend the professional Olaplex treatment for students with very damaged high porosity hair due to this component. However, Sarah doesn't recommend their over-the-counter products due to the ingredients above, and we do recommend being especially aware if you are purchasing them online, to make sure you are getting the "proper formulation." And if you're having the professional Olaplex treatment done at a salon, make sure to ask to see the product packaging so you can verify its legitimacy. Even salons have been known to use counterfeit products, and we can't be sure of what is in them. Note: While some ingredients used in the Olaplex products may not be blacklisted per se, the formulations tend to contain ingredients unsuitable for achieving the aims you're hoping for. As an example, Olaplex No.3 contains a mild surfactant, cetrimonium chloride. While this is entirely safe when used in a cleansing formulation such as shampoo, we generally caution against using surfactants in anything that acts as a hair mask or treatment.