So, what is the deal with sulfates?


This is a question that we are often asked about. Shopping for your hair care products can seem more confusing than ever before. One shampoo line is advertising bounce and shine. They have a fabulous celebrity telling you how you should have these “pro vitamin” goods to keep your hair looking great. 
You also may have also heard that the shampoo you currently use, that has been on the market for many years, may not be all that it is cracked up to be. There are so many types and promised results. Maybe you've just noticed your hair doesn't work with it like it used to or that the "hydrating" is actually drying or the "dandruff control" is making more of it. The labels are often of no help. They can read like stereo instructions, and, what is written in that product list is, usually, more difficult to decipher.
The most common product conversation is over sulfate vs. "sulfate-free". 
But what are they and why should you care?


Sulfates are chemical additives that, at base, are viewed as the foaming agent when you shampoo. They are both a foaming agent and an emulsifier.
Sulfates are seen on labels in many ways. Most commonly, you’ll read it as: Sodium Lauryl Sulfate.

According to the department of Health and Human Services, Sodium Lauryl Sulfate (SLS) has also been seen as: “Sulfuric acid monododecyl ester sodium salt; Sodium dodecyl sulfate; Dodecyl sulfate, sodium salt; Sodium lauryl sulfate ether; Sodium n-dodecyl sulfate; Sodium Lauryl Sulfate”.  It is found in cosmetics and cleaners of many kinds – from your toothpaste and shampoo in the bathroom, to the “scrubbing bubbles” you use to clean it with. 

Sodium Lauryl Sulfate (SLS) is an anionic surface active agent used as an emulsifier in many pharmaceutical vehicles, cosmetics, foaming dentifrices, and even foods”Sodium lauryl sulfate (SLS) has been used extensively as a model irritant in the study of cutaneous irritation.
— Lee 1


It may seem quite disturbing to read that your toilet cleaner has the same ingredient as your shampoo. Granted, there are various levels in which these products have them. A look through the Health and Human Services Searchable List index can give you some indication as to what to expect. That is not all of the information, though, and, who has time to look up the website at every turn of the store?
A look at labels and brand websites can help indicate what's going on inside of the bottle.

Sodium Lauryl Sulfate (SLS) is used in many products for multiple reasons. It is inexpensive, effective and easily used in most anything.
Sulfates are surfactants and, as such, attract the oil and water and emulsify them for easier rinse and disposal. They also keep those water molecules from liking each other too much. Water loves itself and a surfactant will kill that surface tension party quickly.


While that sounds easy enough, what happens when research shows that Sodium Lauryl Sulfate is also a known irritant? Described as the "model irritant in the study of cutaneous irritation", SLS has been used as the model catalyst for studying "acute and cumulative irritation" (Lee 3).
One such study was using SLS as the irritant to study the reactions of "detergent treated skin" and how it healed. They noted that skin would start to heal just before another patch test of diluted Sodium Lauryl Sulfate was added - meaning it was the known go-to irritant.

According to the U. S. National Library of Medicine, "among 242 patients suffering from eczematous dermatitis, the percentage of allergic reactions [to SLS] reached 54.6%" and there are studies on how it has affected skin and hair going back decades. 
One such study conducted in Montreal in 1977, at the Society of Cosmetic Chemistry, surveyed how Sodium Lauryl Sulfate reacted with skin, hair and the keratin that they are both made of.  What they found was that SLS liked to bind "tightly" to the keratin and that a standard washing only removed 30% of the chemical from the hair (Faucher). The study looked over the affects of the chemistry at various diluted levels on untouched hair, bleached hair, and skin cell sections. 
Naturally, the bleached hair had the toughest time with sulfates. Hair that has been compromised, and even damaged, will be porous and will - like a sponge - soak up all that it can. Think of the bleach blonde with the green chlorine issue over summer as an example.
The SLS was found not only to be absorbed during the cleansing process but also to be something that builds - cumulatively - over time. In fact, the study found that compromised hair could soak up an "amount to ten times as much" as what would be initially soaked up in the beginning (Faucher).
Over time, this can cause a problem in effectiveness and what it is doing to your own hair and skin saying that the water using SLS can be "quite immobile" from its tight bind on the keratin. Faucher continues that this means SLS is "unlikely to act as a normal solute in such an environment".  While the unbleached hair in the study had the advantage of the stronger cuticle layer, the "lag" Faucher noted was only about 15 - 30 minutes before absorption began.
An interesting note is how it was also found that SLS has a "great capacity" for being a catalyst that helps other substances make their way into the skin that can be considered irritants, as well. While the sulfate may not bother you, it may be bringing that friend to the party that you hate.


Sulfates can irritate the scalp and hair in many ways.
Maybe it is as simple as feeling more dry. Other times, it may feel heavy from build up. It may also have static or frizz issues. Another issue can be that you feel your scalp is confused or sending you mixed signals. It can feel tight and dry and even get red and irritated while being oily. The great color service you loved could be fading quicker than you'd like. Some products have been known to strip out color even though the bottle says "color safe".
Some of these products, coupled with heat tools, can cause a synthetic hardening around your hair strands and your scalp will want to reject it.
If you are someone with hair that is fragile - such as been chemically treated or you're naturally curly or fine - then sulfates are not helping you in any way. There are countless options out there for quality hair care that can work with many lifestyle needs. 
Taking the extra time to care about what you're putting in your hair and on your skin (scalp is skin, too!) will make a difference.  Take the time to get to know what is in your bathroom. Look into what you're using  - read labels - and remember that your hair needs love, too. 


Works Cited
Bhalekar, Mangesh R. "Evaluation of aqueous extract of Soapnut as surfactant in cosmetics." Journal of Pharmacognosy and Phytochemistry 6.4 (2017): 1318-1320.
Den Yi, Ann, et al. "Skin Barrier Impaired? Two'TEWLs' to tell." Cosmetics and Toiletries 132.1 (2017): 42-55.
Faucher, J. A., and E. D. Goddard. "Interaction of keratinous substrates with sodium lauryl sulfate: I. Sorption." J Soc Cosmet Chem 29 (1978): 323-337.
Freeman, Susanne, and Howard Maibach. "Study of irritant contact dermatitis produced by repeat patch test with sodium lauryl sulfate and assessed by visual methods, transepidermal water loss, and laser Doppler velocimetry." Journal of the American Academy of Dermatology 19.3 (1988): 496-502.
Furmanczyk, Ewa Maria, et al. "Isolation and characterization of Pseudomonas spp. strains that efficiently decompose sodium dodecyl sulfate." Frontiers in Microbiology 8 (2017): 1872.
Horita, Kotomi, et al. "Effects of different base agents on prediction of skin irritation by sodium lauryl sulfate using patch testing and repeated application test." Toxicology 382 (2017): 10-15.
Lee, Cheol Heon, and Howard I. Maibach. "The sodium lauryl sulfate model: an overview." Contact dermatitis 33.1 (1995): 1-7.
Sasseville, Denis. "Alkyl Glucosides: 2017 “allergen of the Year”." Dermatitis 28.4 (2017): 296.