A number of “natural” shampoos claim to be “sodium lauryl sulfate free.

A number of “natural” shampoos claim to be “sodium lauryl sulfate free.” What is sodium lauryl sulfate, and should it be avoided?

—Kristen Lohse, Seattle, WA

Sodium Lauryl Sulfate (SLS) is a synthetic detergent known for its ability to generate a sudsy lather. As a result, the beauty and cosmetics products industry has long used it as a key component in shampoos and other personal care products, citing consumer desire for a foamy bath and shower experience.

But what most happy bathers don’t know about this shampoo ingredient is that it dries the scalp, stripping the skin’s surface of its protective lipids. Follicle damage, hair loss, skin and eye irritation, and allergic reactions such as rashes and hives can result. And if accidentally ingested, SLS can lead to gastrointestinal and/or liver distress.

Despite these potential maladies, nine out of 10 shampoo brands contain SLS or one of its variants. And since the Food and Drug Administration does not regulate beauty or cosmetics products, SLS is likely to remain a staple of the personal care products industry as long as consumers want sudsy shampoos.

While consumers who switch to SLS-free shampoo might miss the sudsy lather they have grown accustomed to in mass marketed products, they can still expect clean and manageable hair. Manufacturers of all-natural shampoos usually opt for good old-fashioned soap instead of SLS-based detergent to get the cleaning done. “It is a fallacy that you need to have foaming bubbles to get it clean,” says Dr. Ron Shelton of the American Academy of Dermatology.

Buyer beware, though: not all shampoos marketed as “natural” or “organic” are SLS-free. Check ingredients lists for SLS or variations such as Sodium Laureth Sulfate (SLES), Ammonium Lauryl Sulfate (ALS), or Ammonium Laureth Sulfate (ALES). All-natural herbal shampoos are least likely to contain SLS-type products. Aubrey Organics, Aveda, and Kiss My Face, among many other companies, make SLS-free shampoos. Check in your local natural foods markets.

CONTACTS: American Academy of Dermatology, (847) 330-0230, www.aad.org; Aubrey Organics, (800) 282-7394, www.aubrey-organics.com; Kiss My Face, (800) 262-KISS (5477), www.kissmyface.com; Aveda, (866) 823-1425, www.aveda.com.