Beard Care Guide · Ingredient Deep Dive

Understanding Sodium Lauryl Sulphate and Finding the Right Beard Shampoo

Beard shampoos free of SLS or SLES have become one of the biggest trends in men's grooming. As people pay closer attention to what's in everything from their food to their face wash, sulphates are one of the first ingredients they question. Is SLS actually that bad? What is it? And what should you look for instead? This is the deep dive.

If you just want the practical version, our companion piece SLS-Free Beard Shampoo: Why It Matters for Facial Skin covers what sulphates mean for your beard specifically. This article is the ingredient science behind it.

What is Sodium Lauryl Sulphate?

SLS stands for Sodium Lauryl Sulphate. It's a common ingredient in personal care products like shampoos, soaps and toothpaste. It's a surfactant, which means it breaks up oils and dirt and creates the lather that lets a product clean effectively. It works well, which is exactly why it's everywhere. The downside is that some people experience irritation or sensitivity to it, which is why SLS-free products exist.

SLS is often described as derived from natural sources, and it is: it's typically made from the fatty acids in coconut or palm kernel oil. But those fatty acids go through several chemical reactions (sulfation and neutralisation) during manufacturing, so despite the natural starting point, SLS is considered a synthetic ingredient because of the processing it undergoes.

Is Sodium Lauryl Sulphate bad?

Not for everyone, and not always. But the potential drawbacks are worth knowing:

• Skin irritation: it can cause irritation, dryness or redness for some people, especially those with sensitive skin or conditions like eczema or dermatitis.
• Eye irritation: if products containing SLS get in the eyes, they can sting.
• Stripping natural oils: SLS can strip skin and hair of their natural oils, leading to dryness. This matters most for dry or delicate hair, and for the sensitive skin under a beard.
• Environmental questions: SLS is biodegradable, but its production can involve palm kernel or coconut oil, and palm oil production has been linked to deforestation.

Reactions vary hugely from person to person. Plenty of people use SLS products with no issue at all; others notice dryness or irritation. It isn't a one-size-fits-all ingredient, which is the whole point of knowing your options.

How is SLS made?

Briefly, for the curious:

• Fatty acid extraction: fatty acids are extracted from the plant oil, usually via hydrolysis.
• Lauryl alcohol production: those fatty acids are converted into lauryl alcohol through hydrogenation.
• Sulfation: the lauryl alcohol reacts with sulphur trioxide to produce lauryl sulphate.
• Neutralisation: finally it's neutralised with an alkali such as sodium hydroxide to produce Sodium Lauryl Sulphate.

What are the alternatives to SLS?

If you're looking for a sulphate-free option, these are the gentler surfactants to look for on an ingredient list:

• Sodium Coco-sulphate (SCS): derived from coconut oil, similar to SLS but generally considered milder.
• Sodium Lauryl Sulfoacetate (SLSa): a milder, less irritating alternative from coconut and palm oils, with good foaming and cleansing.
• Cocamidopropyl Betaine (CAPB): a gentle surfactant and conditioning agent from coconut oil, often combined with others to soften a formula. It also helps soften and detangle hair, which is why it makes sense in a beard shampoo.
• Decyl Glucoside: a mild, plant-based, biodegradable surfactant suitable for sensitive skin.
• Coco-glucoside: another gentle plant-based surfactant from coconut and fruit sugars.
• Lauryl Glucoside: a mild surfactant from coconut or palm oil and glucose, often used in sensitive-skin products.
• Disodium Laureth Sulfosuccinate: less irritating than SLS, with good cleansing and foaming.

A note on CAPB: while it's a milder alternative to SLS and SLES, a small number of people can still react to it. Such reactions are much less common than with stronger surfactants, but it's worth knowing.

The short version

SLS doesn't cause problems for everyone, and some people use it with no issue at all. But even some SLS alternatives can be irritants for certain people, so it isn't a simple good-versus-bad story. Everyone's skin and hair reacts differently.

Whenever you try a new product, patch test first: apply a small amount to a discreet area and wait 24 hours for any reaction. If you've already found something that works and doesn't irritate, stick with it. If you're looking for something new, products formulated for sensitive skin (like a good SLS-free beard shampoo) tend to use the milder ingredients above and are less likely to cause irritation.

FAQ

Part of the RUNESILK beard care guides. Next: why SLS-free matters for facial skin, or how to choose the best beard shampoo for dandruff.