When the Curly Girl Method trend became a hype, a lot of people switched their favorite shampoos for sulfate-free ones. But why? A popular Google search asks, “Why is SLS in shampoo bad?”. After you read this article, you will be able to extensively explain the answer to your friends!
In short, even though sulfates in cosmetics are considered safe, they can excessively dry out your skin and scalp by stripping all the natural and artificial oils off. They are often present not only in shampoos, but also in douche gels, soaps, toothpastes, facial cleansers, and other personal care products.
But let’s get into more detail.
Table of Contents
What are sulfates used for?
Sulfates are used in hair and skincare with one main purpose: to act as foaming agents and get rid of all the dirt and grease on the skin/scalp. When they are combined with water, they create foam which captures the dirt and oils to leave your skin squeaky clean. Besides, they have great antimicrobial properties and kill harmful bacteria and viruses. 
For that reason, sulfates are often used not only in skincare but also in detergents to ensure effective decreasing and sanitation. 
The most commonly used sulfates that you can find in the ingredients lists of various cosmetic products include:
- SLS (sodium lauryl sulfate)
- SLES (sodium laureth sulfate)
- ALS (amonium lauryl sulfate)
Generally, using those sulfate forms as ingredients in cosmetics is considered to be safe. However, there are multiple allegations that sulfates may actually negatively affect your skin and health.  Just imagine that the ingredient, which foams your carwash, also foams your toothpaste. So it’s worthy to look into the potential harms of SLS, SLES, and ALS.
Is SLS safe?
Dryness and eczema
According to the book “Surfactants in Cosmetics”, washing skin with aggressive surfactants (foaming agents) like SLS and SLES, can lead to skin roughness, dryness and scaling.  That being said, the use of sulfates can trigger dandruff.
The same source suggest that if the skin barrier (top skin layer) is previously damaged, the use of those surfactants can impose additional risks of eczema and irritation. Besides, over-drying the skin in people with acne may result in more pronounced acne symptoms and may stimulate the production of sebum (natural skin oil).
*Damaged barrier can be caused by acne, rash, peeling, open cuts, and other.
The American College of Toxicology has studied the potentially irritating effects of SLS, SLES, and ALS. Evidence suggests that when sulfates are applied to the face and stay there for a couple of minutes (or are not rinsed off well), may leave the skin dry and in need of moisture, as they capture not only dirt and grease, but also natural skin oils. This can cause flakiness and irritation. 
That being said, the source suggests that personal care products with sulfates should be used briefly and should be rinsed well.
Another organ (besides the skin) that sulfates can irritate are the eyes. When shampoo or soap gets into your eyes, the burning and stinging is caused by the sulfates reacting with the mucus inside the eye. That being said, evidence suggests that high concentrations of SLS can cause severe eye damage and even blindness. 
According to the book “A Holistic Living Guide”, the systematic penetration of SLS into the skin (therefore, the bloodstream) may lead to SLS retention in the the liver, heart, and brain tissues. Besides, toothpastes with SLS can facilitate the ingestion of this surfactant and may increase the risk of its penetration in the bloodstream. 
That being said, many allegations exist when it comes to the harms of sulfates in the blood, some of them even claiming potential carcinogenic effects. However, no evidence has confirmed linkage between SLS, cancer formation, and organ toxicity.  Due to lack of evidence support, those allegations are still a theory.
How do sulfates affect the body?
People have different sensitivity to sulfates. Therefore, some people (like people with sensitive skin) may experience more pronounced irritation caused by sulfates.
Keeping that in mind, here’s a list of potential irritation symptoms that may indicate you are sulfate sensitive:
- Toothpaste and mouthwash with sulfates may lead to swollen, sore, and bleeding gums.
- Shampoos with sulfates may cause flaky and itchy scalp. Besides, they can “overwash” your hair, making it thin, frizzy and dry.
- Face cleansers with sulfates may lead to dry and flaky patches, tight skin, redness, burning, and in some cases worse acne symptoms.
- Liquid soaps and shower gels with sulfates can make the skin feeling tight and dull, sometimes flaky.