Written by Tenley Haraldson.
Medically Reviewed by Board-Certified Dermatologist,
Dr. Julie Jackson, MD, FAAD.

Since the 1930s, sulfates have been effective cleaning ingredients that remove dirt and oil from a wide variety of surfaces. Over the past few decades, consumers have begun questioning their safety. 

With all of the negative hype, is SLS bad? 

What Is SLS?

SLS in body wash

SLS is just one member of the sulfate family. Derived from petroleum or plant-based sources, these sulfur-containing mineral salts are cheap for companies to produce – and they create rich lather that appeals to consumers. 

You'll find them in hundreds of personal products like shampoos, soaps, shaving cream, and toothpaste. Household cleaning products utilize SLS in laundry detergent, dish soap, carpet shampoo, and surface cleaner.

Fun Fact: Certain food products also use SLS as a thickening agent.

The Most Common Sulfates

  • sodium lauryl sulfate (SLS)
  • sodium laureth sulfate (e.g. SLES, sodium lauryl ether sulfate)
  • ammonium laureth sulfate (ALS)
  • sodium stearyl sulfate
  • sodium lauryl sulfoacetate (SLSA)
  • sodium coco sulfate

How Do Sulfates Work? 

sis free body wash

Sulfates are surfactants, meaning that they lower the surface tension of water so oil, dirt, and grime can mix with it more easily. One side of the molecule attaches to oil while the other side attaches to water. This helps cleaning products lift, dissolve, and rinse impurities away.

What Is SLS?

is sodium lauryl sulfate bad

SLS is the best-known and most commonly-used sulfate. It’s inexpensive and can be derived from a number of sources including petroleum, coconut oil, and even palm oil. 

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Is SLS the Same as SLES?

Although they sound similar – and they’re often used in the same types of products – SLS and SLES are two separate surfactants with two different chemical formulas: 

SLES = CH3(CH2)11(OCH2CH2)nOSO3Na,

SLS = CH3(CH2)11SO4Na.)

SLES is derived from SLS through ethoxylation, when ethylene oxide is introduced to make it less drying and more gentle than SLS. The problem, however, is that ethoxylation can create trace amounts of 1,4- dioxane. 

The FDA acknowledges that 1,4- dioxane is a possible carcinogen. In fact, since the 1980’s, the agency has monitored the risks of 1,4- dioxane and the use of it in certain consumer goods. If it finds its presence in cosmetics poses a health hazard, the FDA will take steps to regulate its use and notify the public accordingly. 

Potential Sodium Lauryl Sulfate Dangers

sodium lauryl sulphate dangers

For every report that claims that SLS is harmful, there’s another that says the opposite. It’s unsurprising that many consumers are unsure what to think about SLS safety. 

The World Health Organization (WHO), however, has detailed several warnings about SLS. It reports that SLS can be harmful if swallowed and may cause eye, skin, and respiratory irritation. 

In a comprehensive 2015 report, the National Institutes of Health (NIH) concluded that, although “years of anti-SLS campaigns have led to consumer concerns and confusion regarding the safety of SLS,” sodium lauryl sulfate is not a danger to human health – when formulated correctly.

Is Sodium Lauryl Sulfate Bad for Skin?

sodium lauryl sulfate side effects

In 1983, the International Journal of Toxicology released a study saying that SLS wasn't harmful as long as it:

  • was used for short periods of time
  • was thoroughly rinsed off of skin
  • didn't exceed a concentration of 1%. 

According to the NIH report (referenced above), sodium lauryl sulfate concentrations of more than 2% can cause skin irritation. But the concentration of SLS in household cleaning products can vary from 1% to 30%, and in personal care products (like bubble baths and body washes), SLS concentrations can range even higher.

sls in soap

SLS in body wash and cleansers is effective at removing dirt and grease, but there’s a tradeoff. Dr. Julie Jackson, MD, FAAD says, “To remove those impurities, SLS also strips away some of the natural moisturizing oils of the skin.”

Not only do surfactants like SLS remove these oils, but some exploratory research also indicates that exposure to a high concentration of SLS can cause skin barrier disruption related to altered skin maturation.

However, more work needs to be done to determine the effects of repeated, low-dose exposure. 

Is Sodium Lauryl Sulfate Safe for Hair?

what is sis in shampoo

Because it creates rich foam that’s easily rinsed away, it's common to find SLS in shampoo and other hair care products. But because it’s such a powerful cleanser, SLS can easily remove too much of the natural sebum on the scalp, causing flaking and making hair feel harsh and dry

Is SLS Toxic to Aquatic Life?

why is sls bad

The WHO also warns that SLS shouldn't be allowed to enter the environment in its raw form, as it can be moderately toxic to aquatic life. Most dilutions of SLS aren’t necessarily toxic, but this depends on the marine species, water hardness, and water temperature.

What enters the water stream from personal care products is a significantly diluted form of SLS that can be considered non-toxic due to its low concentration. However, it has been suggested that chronic toxicity of SLS can also occur at low concentrations.

Why Puracy Doesn’t Use Sulfates

sis free products

Puracy believes that cleaning and personal care products should always consider the health of people, pets, and the environment. We’re one of a handful of companies to utilize coco glycinate. This natural sodium lauryl sulfate alternative produces the rich, satisfying lather in foaming body care products – like our 99.3% Natural Body Wash

Because Puracy was founded on full transparency, you’ll never have to wonder whether our products are safe for your family and your home: They are and always will be.