What is SLS, and should you go SLS-free?

Almost everything in our shop is chosen for what it leaves out, and SLS is near the top of that list. But it’s often talked about as if it were dangerous, which it isn’t. Here’s what SLS actually is, who might want to avoid it, and how to spot it on a label.

What is SLS?

Sodium lauryl sulfate is a surfactant. That means one end of the molecule is attracted to water and the other to oil and grease. This lets it lift dirt off skin, teeth, hair or fabric so it can be rinsed away, and it makes plenty of foam in the process.

It’s cheap, it works, and people have come to expect foam, so it’s in a huge number of everyday products: toothpaste, shampoo, shower gel, hand wash and bubble bath.

Is SLS bad for you?

Not in the way it’s often made out. Regulators consider SLS safe at the levels used in products you rinse off, and there’s no good evidence that it causes serious harm. The issue is irritation.

• On the skin. SLS is so reliably irritating that dermatologists use it as the standard irritant in skin research. It strips oils from the skin, which some people, especially those with dry skin or eczema, notice as tightness, redness or itching.
• In the mouth. A 2022 scoping review of the research on SLS in toothpaste linked it to irritation of the lining of the mouth and, in some people, ulcers. The evidence that switching to SLS-free toothpaste helps with recurring mouth ulcers is limited but promising.

So if your skin is happy and you don’t get mouth ulcers, SLS probably isn’t a problem for you. If you do have sensitive skin or regular ulcers, SLS-free products are an easy thing to try.

SLS, SLES and sodium coco-sulfate

A few related ingredients are worth knowing about:

• SLES (sodium laureth sulfate) is a modified version of SLS that’s generally gentler on skin.
• Sodium coco-sulfate is made from coconut oil and is often marketed as a natural alternative. It’s a mix of surfactants, and the main one is chemically the same as SLS.
• Ammonium lauryl sulfate is a close relative that’s used in some shampoos.

What we sell that’s SLS-free

• Truthpaste adult toothpaste and children’s toothpaste. Made with organic oils and no foaming agent. Read how to use toothpaste from a jar.
• Strong Mint Probiotic Mouthwash. Alcohol-free and SLS-free.
• Vigour8 SLS-Free Family Body Wash. Aloe vera, glycerin and essential oils, in Fruit Punch, Sports or Lemon Burst.
• Patchouli and Sandalwood Soap. A traditional soap made from coconut, rapeseed and shea butter. Real soap is made by a different process and contains no SLS.
• Perspir8 Natural Botanical Deodorant. Free from SLS and SLES, as well as aluminium salts. More in our guide to switching to natural deodorant.

How to spot SLS on a label

Ingredients are listed in order of quantity, using their INCI (international) names. Look for:

• Sodium Lauryl Sulfate
• Sodium Laureth Sulfate
• Sodium Coco-Sulfate
• Ammonium Lauryl Sulfate

The nearer the top of the list, the more of it there is.

Less foam is still clean

The biggest adjustment with SLS-free products is that they foam less. That can feel as though they aren’t working, but foam is mostly for show. What cleans is the surfactant meeting the dirt, plus brushing or rubbing. A gentler wash that leaves your skin comfortable is doing its job.

Shop the guide

See everything in bath and body and oral care.

Questions we get asked

Is SLS the same as SLES?

No. SLES is a modified form of SLS that’s generally milder. Some people who react to SLS are fine with SLES.

Is SLS-free better for eczema?

Many people with eczema find gentler, SLS-free washes more comfortable, and SLS is a known skin irritant. If you have eczema, follow your GP or dermatologist’s advice on emollients and washes.

Do laundry liquids contain SLS?

Some do. Laundry liquids also rely on surfactants. See bio vs non-bio laundry liquid for how ours work.

More from the journal: plastic-free bathroom swaps that actually work and how to use magnesium oil spray.