Could SLS toothpastes be irritating some patient’s mouths?

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  Posted by: The Probe      28th July 2021

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 sulfate-free substitutes has been rapidly increasing among consumers. Research from Google reveals a 180% increase in searches for ‘toothpaste without sodium lauryl sulfate’ in the UK within the past 12 months (June 2020 – June 2021).

While Sodium Lauryl Sulfate (SLS) is a safe ingredient and not harmful, in the last 2 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 as 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, which are now “sulfate-free” as some find that SLS, can dry out and irritate their skin.

SLS is used in most toothpastes 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 is used for cleaning. It is the most commonly used detergent in the beauty industry, and essentially helps liquid substances “foam”.

It was originally developed in 1930 for the laundry industry to clean your clothes, and the sulfate craze quickly became popular in a lot of products, specifically within the Beauty & Personal Care category. It is now found in many everyday cleaning products from floor cleaners to shampoos and toothpastes.

What is the difference between SLS & 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, which 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, and some research from the British Dental Journal and NCBI have shown 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[1]. However, it should be noted 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 as Sodium Lauryl Sulphate toothpaste can increase the frequency of repeated mouth ulcers.[2] Those who suffer with a dry mouth may also benefit from SLS free toothpaste and 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 and 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, and she was over the moon about how much better her mouth felt after only 2 weeks.

What are the benefits of an SLS free toothpaste?

Choosing SLS free toothpaste can be 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 4x fewer lesions after 30 minutes when using Zendium toothpaste which is SLS free compared with a toothpaste containing SLS.[3] A balanced microbiome is also crucial for oral health to protect us against oral disease and Zendium has been shown to shift the oral microbiome towards a healthier state.

Zendium is a daily fluoride toothpaste which has been specially designed without Sodium Lauryl Sulphate (SLS). Instead, it contains a mild, low-foaming agent called stereath-30, which protects the delicate soft tissues of the mouth. It also helps to maintain the activity of the enzymes and proteins in Zendium toothpaste which are clinically proven to boost good bacteria in the mouth to improve the balance of the microbiome[4] and protect against dental problems. 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 which is SLS free.  There is certainly no harm in seeking out sulfate 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:

About the Author:

Dr Surina Sehgal, aka The Foodie Dentist, is an Associate at Rodericks Dental in Denham



In-text: (What are the problems with sulfate-free shampoos, 2021)

Your Bibliography: Dominican Hair Alliance. 2021. What are the problems with sulfate-free shampoos. [online] Available at: <> [Accessed 27 May 2021].

*Stephenson Personal Care. 2021. [online] Available at: <> [Accessed 27 May 2021].

[1] J Microsc Ultrastruct. 2020 Apr-Jun; 8(2): 80. Oral Mucosal Peeling Caused by Sodium Lauryl Sulfate in a 20-Year-Old Female ( & Hassona, Y., Scully, C. Oral mucosal peeling. Br Dent J 214, 374 (2013).

[2] Herlofson BB. Barkvoll P. Sodium lauryl sulfate and recurrent aphthous ulcers. A preliminary study. Acta Odontol Scand 1994: 52: 257-259

[3] Green A et al. JDent 80 (2019) S33-S39, UK 2016, n=30. Zendium (containing Stereth-30) compared to a standard fluoride toothpaste containing SLS. †IPSOS study 2020, Denmark.

[4] Refers to the oral plaque microbiome and the relative abundance of bacterial species with a known association with gum health or disease after 14 weeks of brushing twice a day with Zendium when compared to baseline.

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