Does SLS in shampoo cause hair loss?

No, there is no scientific evidence for this. SLS can cause dryness and irritation on a sensitive scalp, but it has not been shown to affect the hair roots and cause hair loss.

Is shampoo with silicones harmful?

Silicones such as dimethicone are of low concern for skin and hair. Some cyclic silicones have been restricted in the EU because they persist in the environment. They can build up on fine hair; this is a matter of preference, not health.

If the label says fragrance, how can I tell which scents it contains?

The full formula is not listed; however, in the EU, fragrance allergens above a certain threshold (such as linalool and limonene) are listed separately. If you have a fragrance allergy, you can look for these names.

What do the numbers starting with CI on the label mean?

“CI” followed by a five-digit number indicates the dyes that give the product its colour (Colour Index). In the EU, colourants can be listed at the end of the list in any order. Colourless or clear shampoos may not have these numbers at all.

Is preservative-free shampoo safer?

In a product that contains water, the absence of a preservative increases the risk of microbial spoilage. “Preservative-free” products usually rely on special packaging or other preservation methods; they cannot be said to be safer in themselves.

How to read a shampoo label: a guide to sulphates, silicones, preservatives and fragrance

Look at the order first

In cosmetic products, ingredients are listed from most to least according to the amount used in the product. In shampoos, water (Aqua) is almost always at the top of the list, followed immediately by the surfactant that is the product's main cleanser. So the first five or six ingredients largely determine the character of the shampoo.

Ingredients present at less than 1%, however, can be listed in any order. This is why the plant extracts, vitamins or proteins you see near the end of the list are often present in very small amounts. A typical example is a “with argan oil” claim in large letters on the front that appears after the fragrance on the back. For details of how the ordering works, see our ingredient list order guide.

The names in the list are INCI names, used in common around the world. This means you can compare the ingredients of a shampoo sold in Türkiye with one sold abroad using the same names. Plant extracts are usually listed by their Latin names (for example Rosmarinus Officinalis Leaf Extract); this is not a strange chemical but rosemary leaf extract.

Cleansers: sulphates and gentler alternatives

The cleansing and foaming in a shampoo is done by anionic surfactants. The best known are Sodium Lauryl Sulfate (SLS) and Sodium Laureth Sulfate (SLES). Both dissolve oil and dirt effectively; SLS is somewhat stronger and more drying, while SLES is milder.

Claims that these ingredients cause cancer or hair loss have no scientific basis. The real issue is that they can cause dryness and irritation on a sensitive, dry or eczema-prone scalp. Because shampoo is a rinse-off product, contact time is short; most people use sulphate shampoos without any problems.

Cocamidopropyl betaine: a secondary cleanser, mostly used together with sulphates, that boosts foam and reduces irritation.
Coco-glucoside and other glucosides: very mild cleansers made from sugar and plant oil; often seen in “sulphate-free” formulas.
Names such as Sodium Cocoyl Isethionate and Sodium Lauroyl Sarcosinate are also examples of mild anionic cleansers.

We look in detail at who really benefits from sulphate-free products in our sulphate-free shampoo guide.

Silicones: slip and shine

Ingredients whose names usually end in “-cone” or “-siloxane” are silicones. They coat the hair shaft with a thin film, making it easier to comb, reducing static and adding shine. Dimethicone is one of the lowest-concern ingredients for skin and hair; it is not absorbed through the skin and very rarely causes allergies.

With cyclic silicones such as cyclopentasiloxane (D5), the debate is about the environment rather than health: because they break down slowly in nature, the European Union restricted the use of D4 and D5 in rinse-off products in 2020, and a regulation adopted in 2024 extended the restriction to cover D6 and leave-on cosmetics as well (the transition period for leave-on products runs until 2027). On fine hair, silicones can build up over time and weigh the hair down; this is not a health problem but a matter of preference. Using a clarifying shampoo now and then removes the build-up.

Preservatives: why are they there, and which ones need attention?

Because shampoo contains water and is opened and closed in a humid bathroom, it is a favourable environment for microbes. A shampoo without preservatives can quickly go mouldy or grow bacteria; this is why preservatives are a safety feature. For details, see our preservatives in cosmetics guide.

Phenoxyethanol, sodium benzoate and potassium sorbate: common preservatives of low concern within the permitted limits.
Methylisothiazolinone (MIT) and Methylchloroisothiazolinone (MCI): these are strong contact allergens. In the EU they are banned in leave-on products and permitted in rinse-off products only at a very low limit. If you have previously been diagnosed with an allergy to these substances, always look for them on the label.
DMDM Hydantoin and similar ingredients: preservatives that release small amounts of formaldehyde over time; people with a formaldehyde allergy are advised to avoid them.

Fragrance and allergens

The label says “Parfum” or “Fragrance” in a single word, but that word can stand for a blend of dozens of scented ingredients. European law requires certain fragrance allergens to be listed separately when present above a certain threshold. Names you see towards the end of the list, such as Linalool, Limonene, Citronellol and Geraniol, are these allergens.

These ingredients are not a problem for everyone, but they are an important clue for people with a fragrance allergy. If you notice itching, redness or flaking on your scalp, trying a fragrance-free product is a sensible first step. The details are in our fragrance allergens guide.

Conditioning and supporting ingredients

As well as cleansers and preservatives, shampoos contain ingredients that soften the hair and scalp. Glycerin holds in moisture, and panthenol (provitamin B5) helps the hair feel soft and supple. Names beginning with “Polyquaternium” are cationic polymers that make hair easier to comb. Sodium Chloride (salt) is often added simply to thicken the product.

Ingredients such as Citric Acid adjust the product's pH; Disodium EDTA binds the minerals in hard water, helping the shampoo lather better. These are supporting ingredients present in small amounts.

A checklist for reading the label in 30 seconds

Look at the first five ingredients: water and the cleanser that follows it tell you how strongly the shampoo will cleanse.
If your scalp is sensitive, check whether SLS is near the top and whether fragrance is present.
If you have a known allergy (MIT, formaldehyde, certain fragrance ingredients), look for that name directly in the list.
Check the claim on the front against the back: where does the featured plant extract appear in the list?
If your hair feels weighed down, look at the silicones and heavy oils.

Remember: the presence of a single ingredient does not make a product “good” or “bad”. What matters is your hair and skin type, how the product is used and any known sensitivities you have. For persistent itching, rashes or hair loss, it is best to see a dermatologist.

This page is for general information and is not personal medical advice. Warnings on the product label and the advice of a health professional always come first.