Could SLS toothpastes be irritating some patients’ mouths?

SLS toothpasteSurina Sehgal takes a closer look at SLS and explores whether sulphate-free toothpaste might better suit some patients.

As the consumer demand increases for mild formulations and gentle ingredients, it is important for dental professionals to be aware of the ingredients typically found in toothpastes and mouthwashes. And furthermore products that offer whole mouth protection without the need for harsh formulations.

This is especially topical as the desire for sulphate-free substitutes is rapidly increasing among consumers.

Research from Google reveals a 180% increase in searches for: ‘Toothpaste without sodium lauryl sulphate’ in the UK within the past 12 months (June 2020 – June 2021).

While sodium lauryl sulphate (SLS) is a safe ingredient and not harmful, in the last two years there has been a 20% increase in products claiming to be SLS free.

This trend has gained a lot of popularity in all kinds of products. Especially shampoos because SLS is believed to dry out hair and strip away the colour.

There has also been a rise in body washes, soaps and face cleansers. These are now ‘sulphate-free’ as some find that SLS can dry out and irritate their skin.

Toothpastes use SLS to create the foam associated with being ‘squeaky clean’. But does this ingredient have the potential to irritate the tissues in patients with delicate oral mucosa?

What is SLS?

SLS or sodium lauryl sulphate is a chemical agent that we use for cleaning. It is the most common detergent in the beauty industry. It essentially helps liquid substances ‘foam’.

SLS was originally developed in 1930 for the laundry industry to clean your clothes. The sulphate craze quickly became popular in a lot of products, specifically within the beauty and personal care category.

We now find it in many everyday cleaning products from floor cleaners to shampoos and toothpastes.

What is the difference between SLS and SLES?

Some people confuse sodium lauryl sulphate (SLS) with its sister compound, sodium laureth sulphate (SLES), which is also frequently used as a foaming agent in toothpastes, shampoos, body washes and face washes.

SLES is a milder version of SLS, so is not as irritating. But the important thing to remember is that products claiming to be SLS-free usually mean they are free of both compounds.

What relevance does this have for our mouths?

Nearly every toothpaste contains surfactants. These help to create the foam that loosens debris and makes cleaning easier when you brush – this is the effect of SLS.

Another effect of SLS is the distortion in taste we experience after brushing. While this can upset the taste of your morning coffee or orange juice, the majority of us don’t experience any side effects from having SLS in our toothpaste. However, oral tissues are delicate. Some research from the British Dental Journal and NCBI shows this ingredient could be an irritant to some patients’ mouths and can even cause ‘oral mucosa peeling.’ Stripping away the delicate layers of the oral mucosa (Hassona and Scully, 2013).

However, we should note there is no evidence whatsoever that the small amounts of SLS present in toothpaste can cause any long-term health effects. It is a safe ingredient when used minimally. However, there is a specific group of patients who may be more sensitised than others.

Patients with a delicate oral mucosa are more likely to find SLS containing toothpastes less suitable. Especially those with aphthous ulcers. SLS toothpaste can increase the frequency of repeated mouth ulcers (Herlofson and Barkvoll, 1994).

Those who suffer with a dry mouth may also benefit from SLS-free toothpaste. It can also be too harsh for pregnant women and even young children whose mouths are more sensitive.

I personally had a patient who suffered with dry mouth consistently. They complained of a ‘stinging sensation’ after she would brush her teeth.

After long conversations and careful investigation, I recommended her to try and switch to an SLS-free toothpaste, Zendium. She was over the moon about how much better her mouth felt after only two weeks.

What are the benefits of an SLS-free toothpaste?

Choosing SLS-free toothpaste is beneficial to those with more vulnerable mouths.

A clinical study published in the Journal of Dentistry measuring soft tissue lesions on the oral epithelia demonstrated that there were four times fewer lesions after 30 minutes when using Zendium toothpaste, which is SLS-free, compared with a toothpaste containing SLS.

A balanced microbiome is also crucial for oral health to protect us against oral disease. Zendium shifts the oral microbiome towards a healthier state.

Zendium is a daily fluoride toothpaste, which is specially designed without SLS. Instead, it contains a mild, low-foaming agent called stereath-30. This protects the delicate soft tissues of the mouth. It also helps to maintain the activity of the enzymes and proteins in Zendium toothpaste. They are clinically proven to boost good bacteria in the mouth and improve the balance of the microbiome helping protect against dental problems (Zendium data on file).

It can be used for those patients who have a delicate oral mucosa and for the everyday patient too. I personally use it twice daily!

Is SLS-free toothpaste as effective?

For years, brushers thought that their toothpaste needed to foam to be effective. But toothpastes don’t need to contain SLS in order to effectively clean all surfaces in the mouth.

A foamy feel can give the perception of a cleaner mouth and can make it easier to spread toothpaste around. But it is possible to clean the mouth just as effectively using an SLS-free toothpaste.

The SLS-free trend is rapidly growing, including in oral hygiene products.

Although SLS is safe, some can find regular toothpastes with SLS uncomfortable to use and benefit from switching to a toothpaste that is SLS free. There is certainly no harm in seeking out sulphate-free substitutes.

Dentists should be aware of this ingredient and understand the advantages and disadvantages in everyday toothpastes to be able to discuss with patients and be able to recommend suitable products. Especially for those patients who are more likely to find SLS an irritant.

For more information about Zendium please visit

Zendium is offering a free box of patient samples to dental practices for a limited time only. Please visit:


Hassona Y and Scully C (2013) Oral Mucosal Peeling Caused by Sodium Lauryl Sulfate in a 20-Year-Old Female. Br Dent J 214: 374

Herlofson BB and Barkvoll P (1994) Sodium lauryl sulfate and recurrent aphthous ulcers. A preliminary study. Acta Odontol Scand 52: 257-9

Become a Dentistry Online member

Become a member
Add to calendar