Hair conditioner ingredients explained

A typical conditioner list

Conditioners are essentially cationic systems, made as dispersions rather than solutions.¹ A rinse-out conditioner usually combines cationic surfactants with long-chain fatty alcohols or other lipids, and may add cationic polymers such as Polyquaternium-10.² Each group has its own job.

Fatty alcohols: the body of the cream

Fatty alcohols such as cetyl and stearyl alcohol give a conditioner its body and thickness.¹ Cetearyl Alcohol is a mix of C16 to C18 alcohols; the EU database lists emollient, emulsifying, emulsion stabilising and viscosity controlling among its functions.³ Long-chain alcohols such as Cetyl Alcohol and Stearyl Alcohol also have some surfactant properties, of the non-ionic kind.²

They are not the alcohol people worry about. On a cosmetic label, "alcohol" on its own means ethyl alcohol, and the FDA notes that fatty alcohols such as cetyl, stearyl and cetearyl alcohol affect skin quite differently from it.⁴

Cationic conditioners and their EU limits

Cationic surfactants are the backbone of a conditioner. Their positive charge is drawn to the negatively charged hair surface, so they deposit there, especially where hair is weathered or damaged, reduce static and make combing easier.¹ In a 2026 laboratory study of four of them, the longer-chain Behentrimonium Chloride deposited best and significantly reduced wet combing force; it outperformed Behentrimonium Methosulfate, and both did better than the shorter-chain cetrimonium chloride. The same study found no reversal of oxidative damage: conditioners improved manageability without repairing the hair's structure.⁵

The Annex III limits apply when these substances are used for a purpose other than preserving the product, and that purpose has to be apparent from how the product is presented. Cetrimonium Chloride's limit is shared with steartrimonium chloride, and Behentrimonium Chloride's covers its sum with both, while still respecting entry 286.⁹ A label gives no concentrations, so it cannot show how close a product comes to any of them.

Silicones

Silicones such as Dimethicone, dimethiconol, Amodimethicone and cyclomethicone are the synthetic oils used most often in conditioners, and one review rates them above natural oils for film formation, shine and lustre.¹ Another calls silicone the most active and most used conditioning agent.² Silicones in hair products explains how they differ, when they build up, and the EU rules on D4, D5 and D6.

Proteins and humectants

Protein-derived ingredients are drawn to keratin, and can hold the split fragments of a damaged hair end together until the next wash.¹⁰ Hydrolysed proteins are broken into smaller pieces: one review notes that molecules under about 1,000 daltons can diffuse into hair, especially damaged hair.² Hydrolyzed Keratin, partially hydrolysed keratin, is listed in the EU database as antistatic, film forming, hair conditioning and humectant.¹¹ Hydrolyzed Wheat Protein is on Annex III, entry 307, which caps the average molecular weight of its peptides at 3.5 kDa.⁹

The EU defines a humectant as an ingredient that retains or preserves the moisture in a product during use.¹² Glycerin is listed as both humectant and hair conditioning¹³; Panthenol as antistatic, hair conditioning and skin conditioning.¹⁴

Preservatives and scent

Like shampoo, a conditioner is made with water and needs a preservative, and in the EU only preservatives on Annex V may be used, within their limits.¹⁵ Whether a product is rinsed off or left on can change the limit:

• Phenoxyethanol: Annex V, entry 29, up to 1.0% in any product.⁹
• Sodium Benzoate: Annex V, entry 1, up to 2.5% in rinse-off products and 0.5% in leave-on products, measured as benzoic acid.⁹
• Potassium Sorbate: Annex V, entry 4, up to 0.6%, measured as sorbic acid.⁹¹⁶

Scent follows the same split. Fragrance allergens such as Linalool, Annex III, entry 84⁹, must be named on EU labels above 0.01% in a rinse-off product and above 0.001% in a leave-on one¹⁷, so a leave-in conditioner can name allergens that the rinse-out version of the same scent does not. EU fragrance allergen labels explains the list.

What to look for on the label

• The first names after water are usually a fatty alcohol and a cationic conditioner: the base of a rinse-out conditioner.²
• Behentrimonium Chloride, Cetrimonium Chloride and Behentrimonium Methosulfate are cationic conditioners. The methosulfate is not a sulfate cleanser, as what sulfate-free means explains.⁵
• Alcohol on its own, or Alcohol Denat., is ethyl alcohol; Cetearyl, Cetyl and Stearyl Alcohol are fatty alcohols.⁴
• Rinse-off or leave-in matters: the EU limits for cationic conditioners, some preservatives and allergen labelling all differ between the two.⁹¹⁷
• See every role at once by pasting the list into the hair product scanner.

An ingredient list shows what a conditioner is made of, not how much of each it contains or how your hair will respond. It is not a verdict on the product.