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SLS in Toothpaste: The Good, The Bad, & The Ugly

Updated: Jan 15

SLS toothpaste is a dentifrice that contains sodium lauryl sulfate which is a surfactant (soap/detergent) that aids in cleaning the teeth. Its cleaning efficacy is undisputed but the concern about its safety is a hotly debated topic.


Sodium lauryl sulfate
Credit: PubChem

How controversial is it? Controversial enough that it spawned an entire line of toothpastes that are sodium lauryl sulfate free and they are marketed as "all natural toothpastes."


Our purpose here today is to provide you with all of the facts regarding SLS. The good, the bad, and the ugly with this controversial toothpaste ingredient. Hopefully that helps you in making a decision whether or not you should include this in your oral care products.


Table of Contents:


Overview


What is SLS?

SLS (sodium lauryl sulfate) is a surfactant, which is another name for a soap or detergent. It's purpose is to help remove oil and grease by penetrating into them, breaking them up, and washing them away.


Products with SLS:

  • Toothpaste

  • Shampoo

  • Soaps

  • Cleaning and cosmetic products


How it cleans

As with all detergents, the SLS molecule has a water-loving head and a grease-loving tail.


SLS surfactant - hydrophilic head and hydrophobic tail
Credit: Science on the Shelves

Grease removal mechanism:

  1. Grease-loving tail surrounds the oils and fats, forming a circular shape called a micelle.

  2. This leaves the hydrophilic head on the outside of the micelle with the hydrophobic tail on the inside of the michelle.

  3. Since the outside is attracted to water, that is how the grease gets washed away.


SLS detergent micelle formation
Credit: Science on the Shelves

Its cleaning efficacy

SLS's efficacy as a detergent is undisputed because it was so powerful that one of its first documented uses was as an engine degreaser in World War II. It was strong enough to remove the toughest of oils and soot from tanks and airplanes.


As a matter of fact, that same engine degreaser is still in use today and is manufactured by Gunk. They are a company that is privately owned by RSC Chemical Solutions, founded in 1924, based in North Carolina. As you can imagine, if it is good enough to clean engine oil, it can certainly clean your teeth.


What SLS does in toothpaste

SLS in toothpaste is a surfactant that lowers the surface tension by penetrating and loosening up surface deposits (food and plaque) on teeth. This causes the deposits to be emulsified or suspended, which facilitates its removal by brushing.


In other words, sodium lauryl sulfate will break up the food or plaque that is stuck on your enamel, which makes it easier for them to be brushed off.


Characteristics of SLS:

  • Increases foaming and lathering ability.

  • Facilitates removal of food and plaque from teeth.


In summary, toothpastes with SLS have a superior cleaning ability and will leave your mouth feeling squeaky clean.


History of SLS toothpaste

When the first SLS toothpaste was invented is unknown but what we do know is that the first sulfate shampoo by Proctor & Gamble was introduced in the 1930s. However, their iconic Crest toothpaste wasn't brought onto the market until the 1950s. It is possible that it may have been in use for toothpastes prior to that time period but records of it are unavailable.


 

Pros & Cons

Pros:

  • Removes plaque and food.

  • Leaves teeth feeling very clean.

  • Inexpensive ingredient.

  • Uses less toothpaste.

  • Great foaming and lathering.


Cons:

  • Potent detergent that strips away natural oils in the mouth.

  • May prolong canker sore healing time.

  • Potential irritant.

  • Potential allergen.

  • Decreases efficacy of fluoride.


Advantages

If you do not experience adverse effects while using SLS toothpaste, it can provide you with many benefits. It is an extremely effective detergent so it removes plaque and food from your teeth like none other. Ultimately it leaves your mouth feeling very clean.


An often glossed over point is that having sodium lauryl sulfate in your toothpaste can help you save money. Since it foams and lathers very well, it means you'll be using less toothpaste.


Then there is also the fact that this ingredient is inexpensive. Have you compared the prices for this vs the SLS-free toothpastes? The latter costs significantly more.


Disadvantages

The fact that SLS in toothpaste is such a potent detergent is what contributes to its disadvantages. It is such a strong soap that it can strip away natural oils in your mouth and on your teeth, which can lead to soft tissue irritation and inflammation.


Essentially it is a double edged sword. However, not everyone experiences adverse reactions to SLS-based products which include toothpastes, shampoos, soaps, etc.


Note: SLS does not cause white stringy stuff in the mouth.


 

Safety

SLS in toothpaste and other various products are relatively safe to use. As a matter of fact, that is why the FDA approved its use as an additive into food.


However since the early 1990s, misconstrued information about sodium lauryl sulfate has led to concerns about its safety in SLS products. An eruption of egregious claims about the dangers of SLS-based products stoked fears into the public perception of this detergent.


From that was what spawned the anti-SLS campaign ever since... But if you read the misquoted research studies carefully, you'll find that all of these alleged claims are false. Nonetheless, the fear of sodium lauryl sulfate still runs rampant to this day. We suppose that anti-SLS campaign was incredibly effective!


Alleged adverse effects

Over the years, there have been a lot of alleged adverse effects from using SLS products with the most notable being that it is a carcinogen. No, it does not cause cancer and this myth has been debunked several times over.


Institutions which do NOT list SLS as a carcinogen:

  • International Agency for Research on Cancer (IARC)

  • U.S. National Toxicology Program

  • California Proposition 65 list of carcinogens

  • U.S. Environmental Protection Agency

  • European Union

  • American Cancer Society (ACS)


In 1998, the American Cancer Society (ACS) actually published an article attempting to correct the public’s misconception of SLS. However, that fell on deaf ears since the anti-SLS campaign is still alive and well.


List of alleged side effects:

  • Cancer causing agent.

  • Ocular irritation.

  • Dermal irritation.

  • Oral toxicity.

  • Organ toxicity.

  • Hair loss.

  • Sensitization.

Of course, all of the alleged adverse effects above are either untrue or overblown.


Side effects

While toothpaste with SLS is not harmful, it is recognized that it can potentially have some mild harmful effects.

  • Mucosal desquamation.

  • Irritation or inflammation of oral mucosa or dorsum of the tongue.

  • Ulcerations.

  • Decreases bioavailability of fluoride.


The American Dental Association does list it as a possible allergen or contact irritant.


Affects fluoride efficacy

Utilizing sodium lauryl sulfate in toothpaste does decrease the bioavailability of fluoride in the mouth when brushing.


SLS will interfere with the deposition of fluoride on the tooth enamel, which prevents your tooth from using it. Essentially your tooth isn't able to incorporate the fluoride into its structure because the SLS is removing the fluoride.


What that implies is that SLS may decrease the cariostatic potential of fluoride, in other words it decreases the efficacy of cavity prevention. However, if you are anti-fluoride perhaps this is the ingredient for you.


Worsens canker sores

According to research, it is unclear if using SLS toothpaste will increase the frequency and intensity of canker sores. Some studies say that it does while others say that there is insufficient evidence.


Dr Kurthy from KoR Whitening does agree that SLS toothpaste can make canker sores worse since it is a powerful soap. If you think about it logically, a detergent that will strip away lipids from an ulcerated sore in the mouth does sound painful. After all, keeping these areas well moisturized usually helps it heal faster.


Therefore, we would have to agree that it most likely prolongs the healing time for aphthous ulcers. If you suffer from this condition quite frequently we would recommend trying a toothpaste without it to see if it helps.


 

SLS vs SLS-free toothpaste

Features

SLS Toothpaste

SLS-Free Toothpaste

Cost

$

$$

Texture

Foamy & Lathering

Non-foaming

Cleanliness

Very clean

Clean

Cariostatic

Decreases

Neutral

Type

Synthetic

Natural

Fluoride

Yes

Yes

Safety

Safe

Safe

Most toothpaste brands will make SLS-free variations so please read the labels carefully. For instance, Sensodyne toothpaste is mostly SLS-free but they do have some that have it as well.


Is SLS-free toothpaste better?

There are advantages and disadvantages to having SLS as a toothpaste ingredient. We wouldn't say that toothpastes without it are necessarily better or vice versa. They both serve their purpose as a preventative oral care product.


For instance, a whitening toothpaste is most likely much more effective with SLS than one without it. This is because its detergent ability helps to remove stains from your teeth. On the other hand, if you prefer a more natural toothpaste or one that is more gentle on your mouth, perhaps a SLS-free dentifrice would be better for you.


Ultimately, it depends on your personal preference, your wants, and your desired outcome for your oral health. Oral care can be as personalized as you want it to be. Most toothpastes companies do want you to have these options and that explains the difference between sensodyne vs pronamel with the latter being SLS free.


An alternative surfactant that is less harsh would be cocamidopropyl betaine but it does have a slight bitter aftertaste to it.

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About the author: Dr David Chen, DDS

Hello, I'm Dr Chen and I'm an actively practicing dentist in Long Island City, NY. I graduated from Columbia University College of Dental Medicine in 2016 but prior to going to dental school I was already working in the dental field. It's been more than a decade since I first got to know dentistry and let me tell you, time flies by quickly. Since then I've developed a fondness for writing, which is how this all got started!

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Medical Disclaimer:

This blog is purely meant for information purposes and should not be used as medical advice. Each situation in your mouth is unique and complex. It is not possible to give advice nor diagnose any oral conditions based on text nor virtual consultations. The best thing to do is to go in person to see your dentist for an examination and consultation so that you can receive the best care possible.

The purpose of all of this oral health information is to encourage you to see your dentist and to inform you of what you may expect during your visit. Due to the unfortunate nature of dentistry, there isn't really any true home remedies that will get rid of dental problems. Roughly 99.99% of them require in-person intervention by a healthcare professional.

Hint: That is the reason why you can't eliminate seeing dentists in your life!

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