As someone who likes to routinely dye my hair bright pinks, blues and purples, I’m often told by my hairdresser to use sulfate free shampoos. He often talks to me about how multiple bleachings and dying's will leave my hair damaged and brittle, and how sulfate free shampoo will be gentler, both on my damaged hair and on the colour. It seems like every time I take a shower it occurs to me to look into why that is, and whether or not it’s true, but somehow by the time I’m dry, dressed and sitting at the computer I’ve forgotten again. Finally though, here is what I’ve found about sulfates in shampoos.
Shampoo as we know it was invented somewhere near the 1920’s and 1930’s. It was in 1930 that Procter and Gamble made the first sulfate-based shampoo, and since then the formulations haven’t changed all that much. It’s important to remember that ‘sulfate’ isn’t one compound, it’s a common name for any compound containing a sulfate. The ones commonly used in shampoo (historically and currently) are sodium laureth sulfate, sodium lauryl sulfate, or ammonium laureth sulfate.
So what do sulfates do anyways? Well, a couple of things. Primarily they are surfactants, which means they can attract both water and oil molecules, and it’s this property that makes them good for cleaning. They attract the oil on your scalp, then wash away down the drain. It’s also their surfactant status that allows sulfates to create the lather we all know and love in our shampoos.
The problems with sulfates really are that they’re a bit too good at their job as surfactants. Their ability to effectively strip dirt and oil out of our hair means that we also lose a lot of natural oils that protect our hair and scalp, which can leave our heads feeling dry, or even getting irritated and red if you have sensitive skin. Sulfates are also irritants, so if you get shampoo in your eyes a lot (like me), you may notice that sulfate containing shampoos sting a bit more. If you dye your hair (again, like me) you likely will want to use sulfate free shampoos, as sulfate’s efficacy at stripping oils will also strip colour.
Outside of being a bit intense, there are no other problems with sulfates. The myth that they cause cancer is just that, a myth, and they have been studied and approved many times for use in hair products. Shampoos need surfactants to work (they’re made up of 5-30% surfactant), and sulfate-based surfactants are the most effective option getting the job done, but there are other options if you find these shampoos drying your skin out or causing rashes. Do not, however, buy into the media hype that normal shampoos are dangerous or unhealthy.