Is the sodium lauryl sulfate in my shampoo killing me?

All it took was one well-circulated e-mail to get people worried about their shampoo. See more personal hygiene pictures.
John Dowland/PhotoAlto Agency RF Collections/­Getty Images

­­­If you use shampoo to wash your hair, it probably works up into a nice thick lather. This nice th­ick lather, for many of us, really defines the shampooing experience. Imagine, then, discovering that this lather could kill you.

In 1998, an e-mail first made the Internet rounds that instilled fear in shampoo users around the globe. This e-mail, anonymous of course, claimed that your shampoo could be giving you cancer. The culprit, according to the e-mail, is sodium laureth sulfate, also known as SLES. This ingredient creates lather.

In fact, the more common lather-producing agent is sodium lauryl sulfate, SLES's less-expensive cousin. The molecules are very similar, though.

Sodium lauryl sulfate is a detergent, a crystalline salt of sulfated lauryl alcohol. It's good at general cleaning because it's a surfactant -- a substance that breaks up surface tension, the bonds between molecules in the outer layer of a compound. This is how SLS produces lather. It eases those bonds, allowing two separate entities -- say, shampoo and your hair -- to interact more effectively. Without this loosening of surface bonds, shampoo wouldn't be as good at removing dirt and oil from your hair.

SLS is a common ingredient in all sorts of cleaning products. You'll also find it in toothpastes, mouthwashes and, as noted with horror in the anonymous e-mail, garage-floor cleaners.

The most common reaction at this point is: Really? The stuff in our shampoo is also in garage-floor cleaners? How can that be safe?


­It's a bold claim, and the e-mail had the desired effect. Lots of people switched to "all natural" shampoos that proudly assert their SLS-free status, presumably to avoid shampoo-related cancer risk. But are these people really less likely to develop cancer than those of us who use regular old SLS-containing shampoo?

In this article, we'll find out why SLS has gotten a bad rep and see whether our shampoo is really giving us cancer. As it turns out, there are certain risks associated with sodium lauryl sulfate.

So, is our quest for clean hair going to kill us?