Sulfates aren’t evil — they’re just strong. They were originally formulated for industrial degreasing, which is exactly why they became popular in shampoo: they remove oil efficiently and create the thick lather that reads as “clean” to most people.
The problem is efficiency. For hair types that benefit from some natural sebum — curly, coily, color-treated, chemically processed, or dry hair — sulfates strip too much. That’s what creates the dry, frizzy, “squeaky” feeling after washing. Hair absent its natural lipid barrier reflects less light (dullness), tangles more easily (breakage), and loses color molecules faster (fade).
The two sulfates to scan for on a label: sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES). If either sits in the first five ingredients, the formula is a sulfate shampoo regardless of how the marketing describes it. Watch also for ammonium lauryl sulfate — chemically different, functionally similar.