What is Sodium Laureth Sulfate (SLS)?

Sodium Laureth Sulfate (SLS) is one of the most commonly used ingredients in shampoos and body washes. Its main function is to remove dirt, grease, and impurities, as well as create a rich lather, which makes the cosmetic seem more effective at cleansing.

However, there is a lot of controversy surrounding SLS. Critics point to its potential to irritate, dry out and weaken the hydrolipid barrier of the scalp. More and more people are looking for gentler alternatives that will help maintain healthy skin and hair without the risk of irritation. In this article, we will discuss the effects of SLS on hair and present effective substitutes.

What is Sodium Laureth Sulfate (SLS)?

Chemical structure and properties

Sodium Laureth Sulfate (SLS) is an anionic surfactant that belongs to the group of ethoxylated sulfates. It is a synthetic detergent derived from lauryl alcohol, which undergoes an ethoxylation process that reduces its aggressiveness compared to sodium lauryl sulfate (SLS).

SLS works by lowering the surface tension of water, which enables it to effectively emulsify fats and impurities and then rinse them off from the hair and scalp.

Why is SLS commonly used?

Sodium Lauryl Sulfate (SLS) is a highly effective detergent that quickly removes sebum and all impurities from the skin and hair. Thanks to its cleansing properties, it effectively dissolves fats and dirt, which is why it is commonly used in shampoos, shower gels and other hygiene products.

One of the characteristic features of SLS is its ability to foam intensively. The abundant foam not only facilitates the application and distribution of the product, but is also welcomed by consumers, who often associate it with better washing effectiveness. Thanks to this, products containing SLS are popular on the cosmetic market.

Another advantage of SLS is its low production cost. It is one of the cheapest and most easily available detergents, which makes it an attractive ingredient for cosmetics and cleaning product manufacturers. Its use can reduce the cost of manufacturing products while ensuring high washing efficiency.

This substance also gives a distinct feeling of cleanliness after washing the hair or skin. Users often feel that their hair is light, fresh and free of excess sebum. However, the intensive degreasing effect can lead to dry skin and hair, which in some people causes irritation or excessive sebum secretion in the body's defense reaction.

Is SLS harmful?

Irritating and drying effect

Sodium Lauryl Sulfate (SLS) is an effective detergent, but its action can be too aggressive for some skin types. Although it is excellent at removing impurities and sebum, its intensive cleansing properties can lead to negative side effects, especially for people with sensitive skin.

Dermatological studies have shown that SLS can weaken the skin's natural protective barrier. As a result, this can lead to scalp irritation, manifested by itching, burning and redness. Long-term use of products containing SLS can intensify these symptoms, causing discomfort and increased skin sensitivity.

Another problem resulting from the action of SLS is skin dryness. This detergent removes not only excess sebum, but also the natural hydrolipid layer, which is responsible for hydration and protection from external factors. A violation of this barrier can result in a feeling of tightness, dryness and flaking of the skin.

Paradoxically, excessive sebum removal by SLS can lead to increased sebum production. The skin, defending itself against drying out, begins to secrete more sebum, which can result in hair becoming greasy quickly and requiring more frequent washing. This vicious cycle can worsen scalp problems, especially in people prone to seborrhea.

Allergic reactions and hypersensitivity

SLS can cause allergic reactions, especially in people with sensitive skin or a tendency to atopic dermatitis. In people suffering from psoriasis, eczema or acne, it can worsen symptoms.

Does SLS contribute to hair loss?

Many consumers are concerned that Sodium Lauryl Sulfate (SLS) can cause excessive hair loss. Although there is no direct scientific evidence that SLS itself leads to permanent hair loss, its effects may indirectly affect the condition of the scalp and weaken hair follicles.

SLS is a strong detergent that removes grease and impurities, but it can also disrupt the skin’s natural hydrolipid barrier. Studies show that long-term exposure to SLS can lead to irritation, dryness, and inflammation of the scalp. One study published in the International Journal of Trichology noted that chronic scalp irritation can weaken hair follicles and cause hair to become more brittle and thin.

Additionally, people with sensitive scalps or a predisposition to conditions such as seborrheic dermatitis or atopic dermatitis may react more intensely to SLS. Itching, redness and inflammation of the scalp can lead to increased scratching, which in turn damages hair follicles and accelerates the process of hair loss.

Another mechanism that can indirectly affect the condition of hair is excessive degreasing of the scalp. SLS removes sebum, which plays an important role in protecting hair and skin. In response, the body can increase sebum production, which leads to a vicious cycle of greasy hair and more frequent washing. Too frequent use of strong detergents can lead to weakening of the hair structure and even its brittleness and thinning.

Some laboratory studies on animals have shown that high concentrations of SLS can cause skin cell damage and weaken hair follicles, but the doses used in the tests were much higher than those found in cosmetics. It is worth emphasizing that SLS is approved for use in hair care products in safe concentrations, usually not exceeding 15-30% in the composition of the cosmetic .

In summary, SLS is not a direct cause of hair loss, but its potential irritating and drying effects can lead to a weakening of the scalp and hair structure, which can indirectly contribute to hair loss. Those with sensitive scalps or a tendency to irritation should consider milder alternatives such as Sodium Cocoyl Isethionate (SCI) or Sodium Lauroyl Methyl Isethionate (SLMI), which are more gentle on the skin and hair.

Alternatives to SLS – gentle cleaning agents

Although Sodium Lauryl Sulfate (SLS) is an effective detergent, its strong action may be too aggressive for sensitive skin and hair. There are many gentler cleansing substances on the market that cleanse effectively while minimizing the risk of irritation and dryness. SLS alternatives can be divided into several groups, depending on their chemical properties and origin.

Delicate anionic substances

Anionic agents are a group of detergents with good cleaning properties, but among them you can find milder alternatives to SLS.

Sodium Coco-Sulfate (SCS) is a milder version of SLS, derived from coconut oil. While it still has foaming and cleansing properties, its molecules are larger, making it less aggressive to the skin and hair. Studies have shown that SCS causes a lower risk of irritation compared to classic SLS, which is why it is more often used in natural shampoos and products for sensitive skin.

Sodium Lauryl Sulfoacetate (SLSA) is another foaming alternative. Unlike SLS, it does not dry out as much because its molecules do not penetrate as deeply into the skin's lipid layer. It is well tolerated by most skin types and is often used in natural cosmetics and baby products.

Amphoteric detergents

Amphoteric agents are milder detergents that are often used in combination with anionic detergents to reduce their irritating effect.

Cocamidopropyl Betaine is one of the most commonly used ingredients in cosmetics for children and people with sensitive skin. It softens the effects of stronger detergents and improves the quality of foam, so products containing SLS can be less aggressive to the skin. Studies show that Cocamidopropyl Betaine reduces the irritation potential of anionic surfactants by up to 30-40% , making it a valuable ingredient in gentle formulas.

Coco Betaine is a more natural version of coconut betaine, which has similar properties but is even milder. It is used in organic cosmetics and products for allergic skin.

Non-ionic surfactants

Nonionic detergents are among the mildest cleaning substances, making them an ideal choice for people with skin prone to irritation.

Decyl Glucoside is a mild, biodegradable surfactant derived from sugars and vegetable oils. It has a low irritating potential, which is why it is often used in organic products and baby cosmetics. According to dermatological studies, Decyl Glucoside is one of the best tolerated detergents on the cosmetics market.

Lauryl Glucoside is another non-ionic detergent that is gentler than SLS, but still effectively cleanses the skin and hair. It is often used in baby shampoos and products for atopic skin. Studies show that Lauryl Glucoside does not disrupt the skin's hydrolipid barrier, so it helps maintain an appropriate level of moisture.

Natural detergent substitutes

For those looking for completely natural solutions, there are alternatives based on plant and mineral ingredients that effectively cleanse the skin and hair without the use of synthetic detergents.

Soapnut powder (Reetha) and Shikakai are traditional ingredients used in hair care in India. Reetha nuts contain natural saponins that act as a mild detergent, cleansing the scalp and hair without excessive degreasing. Shikakai, on the other hand, has moisturizing and strengthening properties, making it valued in Ayurvedic hair care methods.

Cleansing clays, such as Moroccan clay (ghassoul) , are another natural alternative to detergents. This clay effectively absorbs excess sebum and impurities without damaging the skin's protective barrier. It is especially recommended for people with oily hair and a tendency to irritation.

SLS alternatives include a wide range of gentler detergents that effectively cleanse hair and skin, minimizing the risk of irritation. People with sensitive skin or dermatological conditions can reach for milder anionic, amphoteric and non-ionic substances, as well as natural cleansing ingredients that have been used in hair care for centuries. Choosing the right product depends on individual needs, but more and more people are consciously giving up aggressive detergents in favor of gentler and more skin-friendly alternatives.

How to switch to SLS-free skincare?

Changing your hair care routine to one that does not contain Sodium Lauryl Sulfate (SLS) can be beneficial, especially for those with sensitive, irritated, or excessively oily skin. However, completely eliminating SLS requires a thoughtful approach, as your scalp and hair may need time to adjust to the new routine.

Gradual introduction of shampoos with a gentle composition

Abruptly stopping SLS may cause hair to look less fresh or become greasy more quickly for the first few weeks. This is because the scalp, accustomed to strong degreasing, may initially produce excessive amounts of sebum. Therefore, the best solution is to gradually introduce milder shampoos.

At first, it is worth using a milder SLS-free shampoo in rotation with your current product, e.g. every other wash. This will allow your scalp to gradually get used to milder detergents. After a few weeks, you can switch completely to gentle cleansers such as Decyl Glucoside, Lauryl Glucoside or Cocamidopropyl Betaine .

Regularly exfoliate your scalp to avoid excessive oiliness

One of the challenges that may arise after stopping SLS is that your hair may feel weighed down or your scalp may become too oily. This is a normal reaction of your body as it tries to restore the natural balance of sebum production.

To prevent this effect, it is worth introducing regular scalp exfoliation. Exfoliation helps to remove accumulated sebum, dead skin and cosmetic residues, while improving microcirculation and supporting healthy hair growth. You can use:

• Enzymatic peels – containing natural enzymes, e.g. from papaya or pineapple, which gently dissolve impurities without mechanical friction.
• Mechanical peels – containing peeling particles, e.g. ground apricot seeds, sea salt or sugar.
• Clay peels – based on cleansing clays, such as Moroccan clay (ghassoul) or white kaolin clay, which absorb excess sebum and gently refresh the scalp.

It is a good idea to exfoliate the scalp once every 7–10 days to avoid drying out the skin and to prevent excessively greasy hair.

Testing different formulas to find the best product for your hair

There is no universal recipe for SLS-free care, because each type of hair and scalp reacts differently to different cleansing ingredients. It is worth testing different formulas and observing how the hair behaves after using them.

What to look for when choosing an SLS-free shampoo?

• Type of cleansing agent – ​​for very sensitive skin, non-ionic detergents (e.g. Decyl Glucoside, Lauryl Glucoside) are better, while for people with oily scalp, milder anionic agents (e.g. Sodium Coco-Sulfate) may be better.
• The presence of moisturizing ingredients – vegetable oils, aloe, glycerin and betaine help maintain proper hydration of the scalp and prevent dryness.
• Balance of cleansing and caring ingredients – a shampoo should not only wash effectively, but also support the condition of the scalp and hair.

It is also worth remembering that hair may need time to adapt to the new care. For the first few weeks, it may look different than usual - it may get greasy more quickly, become dull or more flat. This is a natural reaction resulting from the scalp adapting to a more gentle cleansing.

Switching to SLS-free care requires patience and observation of the skin and hair's reactions. The key is to gradually introduce milder shampoos to avoid shocking the scalp. Additionally, regular exfoliation will help maintain the balance of sebum production and prevent weighing down the hair. Testing different formulas will allow you to find the best product tailored to your individual needs. With the right care, hair can become healthier, less prone to drying out and more resistant to damage.

Cutting out SLS in your daily routine can help you achieve healthier scalps and less dry hair. Gentler cleansers may require an adjustment period, but the long-term effects often make up for the initial struggles. It’s worth experimenting with different alternatives to find the best shampoo for your hair and scalp.