SLS and sulphates - the known irritant in your entire beauty regime

As someone navigating the beauty industry on the quest for products for sensitive skin , there are a couple of ingredients that crop up in the hunt which exasperate me more than anything else (apart from poor labelling; but that's another column in itself) due to their obvious irritating effects on the skin. Fragrance , of course, is the frontrunner, and something I avoid at all costs, but sodium lauryl sulphate (SLS) is close behind; with all the knowledge we have and the fact that it is considered a 'known irritant', it amazes me that it's even in skincare at all.

Firstly, to clarify, SLS is deemed 'safe' to use according to The Cosmetic Ingredient Review (CIR) panel, Cosmetic, Toiletry and Fragrance Association (CTFA) and other regulatory bodies, and despite many concerns and speculation over a possible link to cancer, there is no evidence of this (in fact, there appears to be only one study on the topic, undertaken on beagle dogs, which concluded that SLS has no carcinogenic effects). Yet when it comes to irritation, the evidence is clear. So what are sulphates (or sulfates if you're reading in the US) and what makes them so bad for sensitive - and even non-sensitive - skin?

WHAT IS SLS?

"Sulphate compounds are found in many personal care products such as shampoos, facial cleansers and body washes. They are also found in many household and industrial cleaning products," explains GP and skin specialist Dr Anita Sturnham . "They function as surfactants, which means that they can attract water and aid break down of oil and debris, therefore aiding the cleansing process. The main sulphates used in skin care are sodium lauryl sulphate (SLS), sodium dodecyl sulphate and sodium laureth sulphate (SLES)."

The case against SLS

Not all surfactants (which are agents used in detergents) are bad - in fact, far from it, as they're fairly necessary for effective cleansing. But SLS is the one that you'll probably have heard of, and with good reason. In 2013 The Medicines and Healthcare products Regulatory Agency (MHRA) issued a  Drug Safety Update  for aqueous cream, a product long recommended by doctors for eczema, warning that if used as a leave-on moisturiser it could cause skin irritation and thinning of the skin, with SLS deemed the likely culprit. In one study, those who used aqueous cream twice a day found that treated areas were 12% thinner, with an average 20% increase in water loss compared to the untreated skin. The popular cream is now recommended only for use as a soap substitute. Meanwhile, the irritant properties of SLS are so certain that it's used as a marker in scientific studies when testing the safety of other ingredients; in order to establish how irritant a substance is to the skin, its effects are compared to that of SLS.

The irritant properties of SLS are so certain that it's used as a marker in scientific studies when testing the safety of other ingredients

It doesn't stop there, either; while a reaction or irritation might occur initially, the long-term effects are equally concerning, as Content Beauty's founder and organic expert  Imelda Burke  tells me. "The main reason I recommend avoiding SLS in particular is the increased skin permeability you are left with. Several tests have shown that absorption of other chemicals present in skincare, including polyethylene glycols, is increased when SLS has been used prior or is part of the formulation. So if you are prone to sensitivities, irritation may actually increase as the skin's barrier, which is there to protect you from irritation, is compromised."

Why should you avoid it?

Dr Sturnham suggests that potential symptoms of an issue with SLS are redness, sensitivity, dryness, flaking, or a ‘tight’ feeling; most products containing sulphates foam, and your skin will probably feel squeaky clean afterwards - but do you really want your skin to feel like your dishes? That tight, 'clean' feeling is the result of your natural oils being swiped away, your skin drying out and your all-important barrier being impaired. More importantly, if you suffer with any other skin condition it may be making matters worse.

"We do have evidence that sulphates can cause skin irritation and I often find foaming cleansers to be highly aggravating for my patients with acne ,  rosacea  and other inflammatory skin conditions," explains Dr Sturnham. "I generally advise my patients to steer clear of foaming cleansers, to avoid any potential drying or irritant effect."

That goes for SLES, too. "Some studies have suggested that SLES are safer to use than SLS, however, both have a potential irritant effect, so my advice is to avoid all sulphates if possible," says Dr Sturnham. Imelda agrees that neither are worth the risk: "Switching to one of the alternatives, sodium laureth sulfate doesn't solve the problem. Although considered less harsh on the skin, it goes through a process called ethoxylation which has concerns over contamination with 1-4 dioxane, a known carcinogen linked to organ toxicity."

Worryingly, it's not only skincare products that you need to be aware of - you need to check your shampoo and toothpaste labels too.

If you regularly suffer from mouth ulcers, your toothpaste and its foaming action could be to blame, as dentist  Ashish Parmar  explains: "Some commonly used oral care ingredients can cause irritation and abrasions inside of the mouth, which can cause mouth ulcers and gum problems; one research study has shown SLS-free toothpaste reduced ulcers in prone individuals by 80 per cent. If you have reoccurring canker sores or mouth ulcers I would recommend avoiding ingredients such as sodium lauryl sulphate and alcohol.”

Meanwhile, there's been a sudden burst of haircare products launching (or perhaps just redesigning their packaging) boasting their sulphate-free credentials. Ideal for those with sensitive skin and scalps, the trend is more likely down to the popularity of hair colouring and semi-permanent straightening treatments such as the Brazilian blow dry, which hairdressers advise will last longer if you avoid the foaming, stripping qualities of SLS in your shampoo.

What to use instead

So you want to steer clear of SLS - but what's the alternative? Fret not - you needn't give up on fresh breath, clean hair and cleansed skin. It'll just take a bit of savvy shopping, something you'll be more than used to if you're sensitive.

As with the aqueous cream example, SLS is less likely to cause much damage when washed off the skin right away - but why use an irritant on your skin at all? Dr Sturnham recommends using paraben-free, sulphate-free, non-foaming cleansers. "Look for gentle cream or gel based cleansers, rich in natural phytonutrients as cleansing ingredients, such as fruit extracts and natural oil blends. I love wheatgerm and rosehip-based cleansers, rich in skin identical lipids - they gently cleanse the skin, without stripping it of its important oils."

The formula of your chosen product can help counteract any drying effects of surfactants, too, as Imelda explains. "If sensitive I would avoid foaming products and look to soap bars or liquid soaps ideally containing plant-derived glycerin." Hyaluronic acid is another moisture-enriching ingredient that's worth looking out for, too - the more moisture, the better.

Thankfully, there are plenty of products out there that are SLS-free - and they'll usually shout about it, too (though it always helps to check your ingredients lists ). Some brands have specific 'sensitive' or 'free-from' ranges within their product offering, while other brands make a statement and avoid it altogether; meanwhile, any Soil Association-certified organic product will definitely be sulphate-free.

Here's a (by no means finite) list to get you started - because confirmed irritants have no place on your bathroom shelf.

For your skin:

• Skincere - a free-from range, recommended by Dr Sturnham
• Pai - one of my most reliable, organic beauty brands, also recommended by Dr Sturnham and specifically made for sensitive skin
• Child's Farm - a great SLS-free range for children and sensitive skins
• REN - a fragrant brand that's free from sulphates among a large list of other irritants - try the Evercalm range
• Cetraben - a great moisturising range that's SLS-free, fragrance-free and a good alternative to aqueous cream

For your teeth:

• UltraDEX Low-Abrasion Toothpaste - SLS-free, alcohol-free, and even gluten-free
• BOCA toothpaste - a home-grown, homemade botanical toothpaste
• Sensodyne - check the label, but this sensitive brand has some SLS-free products in the range

For your hair:

• Maria Nila - a Swedish colour-friendly vegan haircare range
• Odylique - a Soil Association certified skincare brand with sulphate- and paraben-free shampoos
• Green People - a great organic brand with several SLS-free hair products including a scent-free range
• Philip Kingsley No Scent No Colour range - SLS-free and ideal for those with sensitive scalps

What are your favourite SLS-free products? Let me know in the comments or tweet  @GetTheGloss