Sue's Blog

Do you know the difference? - sulphites or sulphates, SLS or SLES


Failsafer Kate wrote:

“What is the difference between sulphites and sulphates  - should I avoid both? … DermaVeen Conditioner and DermaVeen Bath & Shower Oil are sulfate free (but the DermaVeen Shampoo is not).”

There are 4 classes of these chemicals that failsafers find confusing  – 2 groups of food chemicals and 2 groups of chemicals used in toiletries.

  • Sulphite food additives (AVOID)

All sulphite preservatives - from sulphur dioxide (220) to potassium bisulphite (228) – must be avoided on the RPAH elimination diet. They are some of the most commonly used preservatives in our food supply, strongly associated with asthma and other food intolerance reactions.

 “through the elimination diet, I finally worked out that sulphites are the number one problem for me! When I avoid sulphites, I am perfectly fine!- Erin, from story [1363]

  • Sulphate food additives (OK)

These are completely different chemicals, and do not have to be avoided. They range from sodium sulphate (514) to magnesium sulphate (Epsom salts 518 used as a dietary supplement and laxative) and copper sulphate (519, used in infant formula as a mineral nutrient). 

  • Sodium lauryl sulphate (SLS – failsafers with sensitive skin may have to AVOID)

This chemical is a surfactant, meaning it is used to make foam in personal care products such as soaps, shampoos and toothpastes. SLS is a known skin irritant that can cause dry itchy skin, mouth ulcers and chapped lips (see photo) in people with sensitive skin.

  • Sodium laureth sulphate (SLES – considered to be OK)

SLES is a surfactant similar to SLS except that it is formulated be much milder and not irritate the skin.

Failsafer Lesley wrote:

“I do not find SLS a safe chemical. If I have toothpaste that contains it, I immediately get lots of mouth ulcers. If I wash my hair with a product that contains it I get a very itchy scalp that gradually worsens the longer I use it” – from story [1487]

SLES is considered to be much safer than SLS. Presumably this is why SLES rather than SLS is used in the RPAH-recommended Dermaveen shampoo “natural oatmeal calms and nourishes dry, itchy or sensitive scalps”, and is my favourite shampoo.

However, Lesley continues:

“Some of the products that are similar to SLS but that are considered safer than SLS also cause me problems, only not as severe. The only one shampoo I'm coping with now is Ego QV gentle hair shampoo.”

Similarly, with toothpaste, Lesley says:

“The only toothpaste I've found that I tolerate is Weleda Calendula toothpaste. I'm not sure the calendula is safe, but it smells pretty mild and I don't notice an increase in my symptoms after using it”.

None of the failsafe toothpastes on our list (Alfree, Pharmacy Health and OHS plain toothpaste) contain SLS or SLES – although Oral Hygiene Solutions did years ago, it was reformulated and now clearly states “SLS Free”.  See toothpaste factsheet

Any comments?

We would like to hear from any failsafers with sensitive skins who have experienced problems with recommended failsafe shampoos and toothpastes at This email address is being protected from spambots. You need JavaScript enabled to view it.

NOTE: Failsafers ask about spelling - sulphite or sulfite , sulphate or sulfate. Answer: using PH is the English version, with an  F is the American spelling.

More information

Our sulphites factsheet

Understanding the Difference between Sodium Lauryl Sulfate and Sodium Laureth Sulfate

In the medical journals

Thongprasom K. Glycerin Borax Treatment of Exfoliative Cheilitis Induced by Sodium Lauryl Sulfate: a Case Report. Acta Stomatol Croat. 2016;50(2):158-161. A case study of a 19-year-old who had experienced scaly and peeling lips for more than 7 years (see photo above)  …  when she switched to an SLS-free toothpaste she started improving within 3 weeks.

Brown RS et al, Inflammatory reaction of the anterior dorsal tongue presumably to sodium lauryl sulfate within toothpastes: a triple case report. Oral Surg Oral Med Oral Pathol Oral Radiol. 2018;125(2):e17-e21. The authors report 3 patients with oral pain secondary to inflammation of the dorsal anterior tongue. These patients were all using toothpastes with SLS as an ingredient … The lesions and pain resolved upon switching to toothpastes without SLS as an ingredient.

Blondeel A et al, Contact allergy in 330 dermatological patients. Contact Dermatitis. 1978 Oct;4(5):270-6. Of 330 patients with dermatitis, 6.4% reacted with testing with sodium lauryl sulfate.

McLelland J et al, 'Irritants' increase the response to an allergen in allergic contact dermatitis. Arch Dermatol. 1991;127(7):1016-9. In people with allergic contact dermatitis, the use of the irritant SLS was showed increase to increase the size of the reaction to the allergen.

This article argues that SLS is safe in cleaning products but not for some people in body application products:

Environmental chemical exposure is a major concern for consumers of packaged goods. The complexity of chemical nomenclature and wide availability of scientific research provide detailed information but lends itself to misinterpretation by the lay person. For the surfactant sodium lauryl sulfate (SLS), this has resulted in a misunderstanding of the environmental health impact of the chemical and statements in the media that are not scientifically supported. This review demonstrates how scientific works can be misinterpreted and used in a manner that was not intended by the authors, while simultaneously providing insight into the true environmental health impact of SLS. SLS is an anionic surfactant commonly used in consumer household cleaning products. For decades, this chemical has been developing a negative reputation with consumers because of inaccurate interpretations of the scientific literature and confusion between SLS and chemicals with similar names. Here, we review the human and environmental toxicity profiles of SLS and demonstrate that it is safe for use in consumer household cleaning products.

Environ Health Insights. 2015 Nov 17;9:27-32. doi: 10.4137/EHI.S31765. eCollection 2015. Human and Environmental Toxicity of Sodium Lauryl Sulfate (SLS): Evidence for Safe Use in Household Cleaning Products. Bondi CA, Marks JL, Wroblewski LB, Raatikainen HS, Lenox SR, Gebhardt KE.