What an INCI name identifies

An INCI name is a label name. Its job is to make the ingredient list on a carton sold in Lisbon read the same as the one on a carton sold in Chicago. It does that job well. It does almost nothing else.

A formulator assembling a product dossier meets the gap early. The INCI name is the string that must appear on the label, so it starts to feel like the material's identity. It is not. Two containers carrying the same INCI name can come from different starting materials, by different manufacturing routes, in different salt forms, at different assay levels, in different carriers, and both can be correctly labelled. The name is a naming convention. It is not a specification, not a grade, not a purity claim, and not a statement that a material is suitable for anything. Everything that distinguishes one supplier's material from another's lives outside it.

Who assigns INCI names, and on what basis

INCI names are developed by the International Nomenclature Committee and published by the Personal Care Products Council in the International Cosmetic Ingredient Dictionary and Handbook, also distributed electronically as wINCI. The committee is drawn from industry, academia, regulatory authorities and sister associations.

A name is assigned on application. A supplier submits information about a material and the committee applies its nomenclature conventions to produce a name in controlled form. The output is a name. It is not an assessment of the material, and it is not a finding about the material's quality. The Council states this directly: an ingredient having an INCI name does not mean the ingredient has been approved for use in cosmetics, or that its use in a cosmetic product complies with applicable laws and regulations.

INCI names are also not proprietary. Once established, a name describes a class of material and is used by everyone supplying material that fits the convention. A trade name belongs to a supplier. An INCI name does not. That is exactly why it works as a label name, and exactly why it cannot work as a specification.

How the name becomes a labelling obligation

In the European Union, Article 19(1)(g) of Regulation (EC) No 1223/2009 requires a cosmetic product to bear a list of ingredients expressed in common ingredient names taken from a glossary compiled and updated by the Commission under Article 33. That glossary is required to take account of internationally recognised nomenclatures, INCI among them. The glossary is republished periodically. The current instrument is Commission Implementing Decision (EU) 2025/1175 of 16 June 2025, which repealed Implementing Decision (EU) 2022/677 and became applicable on 30 July 2026.

Two consequences follow for a dossier. The operative name for an EU label is the glossary entry, not whatever a dictionary edition or a supplier datasheet happens to print. And glossary entries move. Names are added, revised and withdrawn between editions, and each edition carries its own transition period. A dossier that records which glossary version was in force when the label text was fixed is easier to defend later than one that records only the name.

The United States handles the same problem differently. 21 CFR 701.3 sets a hierarchy of naming sources for the ingredient declaration rather than a single glossary. It looks first to names established by the Commissioner under § 701.30, then to a list of named compendia beginning with the CTFA Cosmetic Ingredient Dictionary and including specified editions of the United States Pharmacopeia, the National Formulary, the Food Chemicals Codex and USAN, then to the name generally recognised by consumers, then to the chemical or other technical name or description.

The practical point is not that the two regimes disagree. It is that in both cases the legally operative name belongs to the regime, and the nomenclature convention feeds it. Reading the convention is not the same as reading the requirement.

What the shared name leaves open

Assume two suppliers offer material under the same INCI name, and that both are naming it correctly. The following can still differ, and none of it is visible in the name.

• Manufacturing route — chemical synthesis, fermentation, enzymatic conversion, or extraction from a natural source. The route determines which process residues are plausible in the first place.
• Salt form and counterion. Acetate, trifluoroacetate, hydrochloride and free base are different contents in the container, and the counterion usually does not appear in the INCI name.
• The basis on which content is expressed. A figure stated as the peptide and the same figure stated as the salt are not comparable numbers.
• Chromatographic purity versus content. Purity describes the relative area of a peak in a separation. Content describes how much of the weighed powder is the substance of interest. Our note "Purity is not peptide content" covers the distinction.
• Carrier and matrix. Many cosmetic-facing materials are supplied as solutions or dispersions, and the water, glycol or other carrier may or may not carry its own INCI entry.
• Physical form, particle size, and whether the material is supplied as a powder or already in a liquid system.
• Residual solvents, and whether they are tested for or only argued absent from process knowledge.
• Microbiological and endotoxin testing — whether it is performed at all, by what method, and against what limits.
• The impurity and related-substances profile, which is often route-specific and therefore supplier-specific.

All of it can matter to a formulation, to a stability programme, and to what the finished-product dossier is able to say about composition.

INCI, CAS and EC numbers are three different kinds of identifier

They are frequently printed side by side on a datasheet, which invites the assumption that they are three ways of saying the same thing. They are not.

A CAS Registry Number is assigned by CAS, a division of the American Chemical Society, and designates one specific substance. That precision is about chemical identity and nothing else. A CAS number carries no grade, no purity, no salt form as supplied, no carrier, and no supplier.

An EC number comes from the European Community inventory of substances — the EINECS, ELINCS and NLP entries — and serves as a European regulatory identifier for a substance. The same limitation applies. It identifies a substance, not a product, and not a batch.

INCI sits at a different level again. An INCI name may correspond to one CAS number, to several, or to none at all; extracts, hydrolysates, blends and many biotechnology-derived materials have no single clean CAS assignment. CosIng lists INCI names alongside CAS and EINECS or ELINCS numbers where they exist, which is a convenience rather than an equivalence. Two materials can share an INCI name and not share a CAS number. Two materials can share a CAS number and differ in every parameter a specification covers. Neither identifier replaces the other, and neither replaces a specification.

What to ask the supplier for

The gap between a name and a specification is closed by documents, not by further identifiers. For a product dossier, request the following in writing, and keep the versions you were given.

1. The supplier's product specification: parameters, test methods and limits, carrying a document number and a revision.
2. A certificate of analysis for the lot you actually received, rather than a typical or representative one. Our note on reading a certificate of analysis sets out what that document claims and what it does not.
3. A full statement of composition — everything present in the container, including carrier, counterion, and any process aid or preservative, with the INCI name of each component where one exists.
4. The salt form, and an unambiguous statement of the basis on which content is expressed.
5. The manufacturing route and the nature of the starting materials, at whatever level of detail the supplier will commit to in writing.
6. CAS and EC numbers where they exist, together with a statement of which component of the supplied material each number refers to.
7. The retest or re-evaluation date, the basis for it, and the storage conditions the supplier ties it to.
8. Any grade designation, in writing. "Cosmetic grade" has no fixed cross-industry definition. It means what the accompanying specification says it means, and nothing beyond that.

An INCI name is a good identifier for the single purpose it was built to serve. It tells a regulator and a consumer what class of ingredient is present, in a form that stays consistent across markets and languages. It was never designed to tell a formulator what is in the drum. That question is answered by a specification, a lot-specific certificate, and a supplier willing to put the rest in writing.