Curly Hair Product Ingredient Glossary

Headline finding: the Cosmetic Ingredient Review (CIR) has published safety conclusions for all seven ingredients below, and four of them come with a condition, such as being formulated to be non-irritating or to restrict peptide size. The CIR assesses ingredient safety, not products, and not whether an ingredient works for your hair.

The names on a label are INCI names, from the International Nomenclature of Cosmetic Ingredients. The European Commission's CosIng glossary of common ingredient names takes account of INCI, and the Commission says the glossary is not a list of ingredients authorised for use in cosmetic products and is not exhaustive. Our guide to choosing curly hair products explains how to read an ingredient list.

The glossary

Notes on each ingredient

Glycerin

CIR lists humectant and hair conditioning agent among glycerin's functions, alongside several others. Humectants attract water. Its conclusion is the plain one: safe in the present practices of use and concentration described in the assessment.

Cetearyl Alcohol and Cetyl Alcohol

These are fatty alcohols, not the short-chain alcohols found in some stylers. The 1988 report covers cetearyl, cetyl, isostearyl, myristyl and behenyl alcohols together and describes long-chain alcohols in lotions as emollients, emulsion stabilisers, viscosity control agents, coupling agents and foam stabilisers.

Dimethicone

Dimethicone is one of 30 ingredients in CIR's 2022 amended report on dimethicone, methicone and substituted-methicone polymers. The conclusion carries two conditions: the ingredients must be formulated to be non-irritating, and the Panel found the data insufficient to decide on safety in products that may be incidentally inhaled, with airbrush devices given as the example. That second point does not concern hair creams and rinse-off conditioners.

Hydrolyzed Wheat Protein and Hydrolyzed Keratin

Protein ingredients are the ones people mean when they ask whether their hair needs protein. For wheat, CIR's conclusion depends on peptide size: safe when formulated to restrict peptides to a weight-average molecular weight of 3500 Da or less. The report found these ingredients will not provoke immediate Type 1 hypersensitivity reactions in sensitised individuals and will not induce sensitisation when polypeptide lengths do not exceed 30 amino acids. For keratin, the 2016 report found the keratin-derived ingredients, including Hydrolyzed Keratin, safe in the present practices of use and concentration. Our moisture and protein guide covers how these feel on hair.

Shea butter

CIR lists shea butter as an occlusive skin-conditioning agent and a non-aqueous viscosity-increasing agent. The 2017 report covers 13 shea-derived ingredients and sets one condition: that they are formulated to be non-sensitising.

Sodium Lauryl Sulfate

This is the oldest assessment in the table, from 1983, so check cir-safety.org for anything newer before you rely on it. It found sodium lauryl sulfate and ammonium lauryl sulfate safe in formulations designed for discontinuous, brief use followed by thorough rinsing, with a 1 per cent ceiling in products meant for prolonged skin contact. It reports irritation in patch tests at 2 per cent and above, and flags possible hair damage as something formulators should consider. Whether a sulfate cleanser suits your scalp is a personal call, covered in our wash day routine.