exlinea Pro Peptide Serum: The INCI List, Read Line by Line

By What Peptides Editorial Team · Updated 2026-09-14 · Part of Peptide Structure, Classification & Scientific Terminology

An INCI list is not a recipe, but it is a structured document, and it can be read. The structure rests on one split: ingredients present above one percent are declared in descending order by weight, and everything at or below one percent may be declared in any order the manufacturer chooses. Almost everything else you might want from a cosmetic label follows from that. You can prove that an ingredient is below one percent. You cannot prove that it is above any particular figure, and you cannot prove a percentage at all.

Learning the bands makes the reading fast, because the same categories appear in the same places in almost every water-based product. For the conventions behind the names themselves see our peptide structure and classification guide; for a second worked example on a different product type see reading a retailer ingredient panel, and for the naming of the product itself see how a full product name is parsed.

The bands of a cosmetic ingredient list

Band one is the solvent and humectant phase: aqua first, then glycerin, propanediol, butylene glycol or pentylene glycol. These are usually the only entries comfortably above a few percent. Band two is texture: carbomer, xanthan gum, hydroxyethylcellulose, an acrylates crosspolymer, or a hyaluronate salt, all of which do their work at fractions of a percent. Band three, where the product has one, is the emollient phase: esters, squalane, dimethicone, a light oil. Band four is the actives block, and this is where peptide entries live.

Band five is adjustment: citric acid, sodium hydroxide or tromethamine, present in whatever quantity the pH requires. Band six is preservation: phenoxyethanol, ethylhexylglycerin, benzyl alcohol, sodium benzoate, potassium sorbate. Band seven is fragrance and colour, declared as parfum or by name. Bands four through seven normally fall at or below one percent, which is the single most useful thing to know about a cosmetic label, because it tells you which half of the list can support an inference and which half cannot.

Three details complicate the reading slightly. Botanical and fermentation entries can be mixtures in their own right, so a single name may stand for a solution rather than a substance. Certain fragrance allergens are listed separately even when they arrive as part of a fragrance, which lengthens the tail of the list without adding materials. And in the European Union a nanomaterial must be followed by the word nano in brackets, so an entry such as a UV filter can carry a note that changes how it should be read.

The one percent rule and what it permits

In the United States the requirement is descending order of predominance, with two exceptions: ingredients present at one percent or less may be listed in any order, and colour additives may be listed separately in any order. Fragrance and flavour may be declared as such rather than by component. The European Union applies a comparable ordering rule for materials at one percent or less, and adds a specific labelling requirement for nanomaterials, which must be followed by the word nano in brackets. Both systems therefore divide the list into an ordered region and an unordered one.

Three consequences follow. First, if an entry appears after a preservative used at its typical maximum, it is almost certainly at or below one percent, because the preservative sets a practical ceiling on that part of the list. Second, two products cannot be compared by position alone when both entries sit in the unordered region. Third, a single word such as parfum can stand for many materials, with only listed allergens named separately, so the length of a list is not a guide to how much is in it.

One more pattern is common enough to name. Some brands print a figure on the front of the pack, such as a percentage for a named complex, and that figure is a claim the seller is responsible for rather than a regulated declaration. It is still useful to a reader, because it gives an upper bound for everything below the corresponding entry: if a complex is stated at two percent and a peptide entry sits below a preservative, the peptide is below one percent regardless of how the complex is described. Take the printed figure as a claim and the list as the declaration.

• Provable: an ingredient sits at or below about one percent, if it follows the preservative block.
• Provable: two products declare the same ingredient, whatever their relative positions.
• Not provable: any percentage, for any ingredient, from the label alone.
• Not provable: that a higher position in the unordered region means a larger amount.
• Not provable: anything at all about the composition behind the word parfum.

A worked reading

Take a representative serum declaration: aqua, glycerin, propanediol, dicaprylyl carbonate, squalane, dimethicone, sodium hyaluronate, hydroxyethylcellulose, acetyl hexapeptide-8, palmitoyl pentapeptide-4, tocopherol, phenoxyethanol, ethylhexylglycerin, citric acid, parfum. The first three entries are the solvent and humectant band and are the only ones likely to be above a few percent. Dicaprylyl carbonate, squalane and dimethicone form the emollient band, probably in the low single digits, since a serum carries a small oil phase held in place by the polymer that follows.

Sodium hyaluronate and hydroxyethylcellulose are texture materials that work at fractions of a percent up to around one percent. The two peptide entries come next, in the actives band, and then tocopherol as an antioxidant. Phenoxyethanol is typically used at or below one percent and ethylhexylglycerin below it, so everything from that point down, including the peptides, is declared in the unordered region. The only defensible conclusion is that both peptides are declared at or below about one percent, and nothing about their exact amounts.

This page is part of the Peptide Structure, Classification & Scientific Terminology guide.