Understanding SLS, SLES, SLSA and SCI: Choosing a Gentler Shampoo for Your Hair

Walk down any supermarket aisle and you'll see shampoos proudly labelled "sulphate free", "natural", or "gentle". But what do ingredients like SLS, SLES, SLSA and SCI actually do, and why do they matter?

These ingredients are all surfactants – cleansing agents that remove dirt, oil and product build-up from your hair and scalp. The difference lies in how effectively they clean and how gentle they are on your skin and hair.

What is SLS?

SLS (Sodium Lauryl Sulfate) is one of the most common cleansing agents found in traditional shampoos.

It creates a rich lather and removes oil very effectively. While many people use products containing SLS without issue, it can be too cleansing for some individuals, particularly those with dry hair, colour-treated hair, sensitive scalps, eczema, psoriasis or dermatitis.

Because SLS is such an effective cleanser, it can sometimes leave hair feeling stripped or dry.

What is SLES?

SLES (Sodium Laureth Sulfate) is a modified version of SLS.

It still produces excellent foam and cleansing performance but is generally considered milder than SLS. This is why SLES is commonly found in many mainstream shampoos and body washes.

While gentler than SLS, some people with sensitive skin still prefer to avoid it.

What is SLSA?

SLSA (Sodium Lauryl Sulfoacetate) is often confused with SLS because the names sound similar.

However, SLSA is a completely different ingredient. It produces abundant, creamy foam and is generally considered much gentler than either SLS or SLES.

SLSA is commonly used in premium shampoo bars, bubble baths and bath products where a luxurious lather is desired without harsh cleansing.

What is SCI?

SCI (Sodium Cocoyl Isethionate) is one of the mildest surfactants commonly used in shampoo bars.

Derived from coconut fatty acids, SCI creates a rich, creamy lather while helping to maintain the hair's natural moisture balance.

Because of its mildness, SCI is frequently used in products designed for sensitive scalps, dry hair and colour-treated hair.

Many formulators consider SCI the gold standard surfactant for gentle shampoo bars.

Are SCI and SLSA Natural?

This is one of the most common questions people ask when choosing a shampoo bar.

SCI and SLSA are not natural ingredients in the same way that goat milk, aloe vera or olive oil are natural ingredients. However, they are commonly described as plant-derived surfactants because they are made from fatty acids obtained from vegetable oils, most commonly coconut oil.

These ingredients are processed to create gentle cleansing agents that effectively remove dirt, excess oil and product build-up from the hair and scalp.

For this reason, many formulators and customers consider SCI and SLSA to offer the best of both worlds: the performance of modern hair care combined with renewable, plant-based starting materials.

This is why SCI and SLSA are frequently found in premium shampoo bars, particularly those designed for sensitive scalps and customers looking for a gentler alternative to traditional sulphate-based shampoos.

Comparing the Four

From strongest cleansing to gentlest cleansing, these ingredients are often viewed as:

SLS → SLES → SLSA → SCI

This doesn't mean one ingredient is "good" and another is "bad". The best choice depends on your hair type, scalp condition and personal preferences.

Why We Chose SCI, Cocamidopropyl Betaine and SLSA

At Capertee Valley Soaps, we wanted to create a shampoo bar that cleans effectively while remaining gentle on both hair and scalp.

Our shampoo bars combine:

• SCI for gentle cleansing and creamy lather

• Cocamidopropyl Betaine to improve mildness and foam

• SLSA to create a luxurious, bubbly wash experience

These gentle cleansers are blended with conditioning ingredients and botanical extracts, including goat milk powder, hydrolysed oat protein, white tea extract, manuka honey, chamomile and calendula.

Panthenol (Pro-Vitamin B5) is included to help attract and retain moisture, while conditioning ingredients help leave hair feeling soft, smooth and manageable.

For our dry hair formula, nourishing cocoa butter and moisturising ingredients provide additional care for hair that needs extra hydration.

The Bottom Line

A shampoo doesn't need harsh detergents to leave your hair feeling clean.

Modern shampoo bars can provide excellent cleansing, rich lather and a luxurious washing experience while using gentler, plant-derived surfactants such as SCI, Cocamidopropyl Betaine and SLSA.

If you have a sensitive scalp, dry hair or simply prefer a gentler approach to hair care, understanding these ingredients can help you choose products that better suit your hair's needs.

At Capertee Valley Soaps, we believe effective hair care can be both gentle and nourishing, combining modern formulation with naturally inspired ingredients to help your hair look and feel its best.