“I checked—it has the same INCI, so it’s the same.” I hear this often, and in a sense it is a good sign: it means you have stopped trusting the packaging and learned to turn the bottle around.
The problem is that this conclusion does not hold up. Two products can have an almost identical ingredient list and still be two completely different formulations, with different effects on the skin.
There is no deception behind it. INCI was created for a precise purpose, and that purpose is not to tell you about the formula: it is to allow you to recognize a substance to which you are already sensitized. It is used to identify, not quantify. All the confusion stems from this.
[INDICE:h2]
Elisa Avalle · Founder and dermocosmetics specialist
Knowing how to read a label does not make you less capable of choosing. It makes you harder to convince—which, in our industry, is an excellent starting point.
Langhe, September 13, 2026
What is INCI?
INCI stands for International Nomenclature of Cosmetic Ingredients. It is the nomenclature that makes it possible to list every ingredient under the same name, regardless of the country in which the product is sold. It is intended to make information comparable and, above all, to help people recognize a substance they need to avoid.
The three things INCI tells you with certainty
- Which substances are present in the product, under their international names.
- The descending order of concentration, but only down to 1%.
- Fragrance allergens subject to individual declaration when they exceed the applicable thresholds.
That 1% detail is the most important and least known. Ingredients above 1% must be listed from the most abundant to the least abundant. Below that threshold, the order is flexible: whoever prepares the label can arrange them as they prefer.
In practice, this means that an active appearing halfway down the list could be present at 0.9% or 0.05%. You cannot tell the difference from the INCI, and even someone who formulates products professionally cannot determine it with certainty.
“Below 1%, the order is flexible. It’s the line in the regulations that explains half of the disappointments with cosmetics.”
The four things INCI does not tell you
The percentages
No concentration is disclosed. A product may contain an active at the dose indicated in the technical data sheet or at a fraction of that dose, sufficient only to be able to name it. In both cases, you read the exact same line on the label.
Which version of the ingredient
Under the same INCI name, there can be raw materials that differ greatly from one another. Molecular weight, degree of purity, extraction method, free or encapsulated form, and stabilization can all vary. These differences affect how they behave on the skin and can make the cost of the raw material vary by as much as tenfold.
Hyaluronic acid is the clearest example: high- and low-molecular-weight forms have the same name on the label and do two different things.
The manufacturing process
The INCI doesn’t show anything about how the product was made. The order of addition, temperatures, times, homogenization, and emulsifying system are what determine stability, active-ingredient release, and sensory properties. Two formulas with the same ingredients, processed differently, produce two different products — and that’s also why one cream pills and another doesn’t.
The context
An active ingredient never works alone. It works within a system that can promote or hinder its penetration, protect it from oxidation, or let it degrade.
The textbook case is vitamin C, which is naturally unstable: paired with ferulic acid and vitamin E, it holds up much better. On the label, you see three names. What you don’t see is that the third exists to make the first work.
FERULIC + HA SERUM Brightening antioxidant serum for the face based on Vitamin C & Ferulic AcidEFFECTS: Lightens blemishes Stimulates c... Discover FERULIC + HA SERUM
Dupes and originals: why copying the list isn’t enough
The reasoning applies fully to dupes, products designed to resemble an original at a lower price. I’m not saying they’re worse: sometimes they’re honest products at a fair price, and that’s perfectly fine. I’m saying that “same INCI” is a similarity of labels, not proof of equivalence.
And the difficulty of getting close to an original is not the same in every case.
- With serums, getting close is more feasible: they are often relatively simple, water-based systems, with fewer variables at play.
- With creams, it’s much more complicated, because the emulsion is the product. The texture comes from the process, not just the ingredients.
- With fragrances, it’s extremely complicated, and anyone who has smelled a dupe alongside the original already knows that.
Price is not a guarantee, in either direction
There’s one last thing you can’t see in the INCI: how much the raw materials cost. An active ingredient dosed properly has a non-compressible cost, and this sets a floor — below a certain price threshold, certain formulas cannot exist.
But it’s a floor, not a ceiling. I sometimes read the labels of very expensive cosmetics and find almost nothing meaningful in them. A high price proves nothing: it is simply a price. I wrote in the article about what happens before an active ingredient goes into a cream about how it is decided whether an active ingredient goes into a formula, and at what cost.
How I use INCI
I don't use it to decide whether a cosmetic works, because it can't tell me that. I use it to ask myself three questions.
- Are the ingredients the product promises in positions compatible with that promise, or do they appear at the end, after the preservatives?
- Does the formula make sense for the type of skin it is intended for, or is it designed to look good on the label?
- Does the brand state anything verifiable about concentrations and testing, or does it merely name the active ingredient?
The rest must be asked of whoever formulated the product, or whoever recommends it to you. This is also why we chose pharmacies: at pharmacies that distribute LeLang, you can also bring the products you already use and have someone read the label with you. The INCI tells you what's inside, not whether that product makes sense for you — and that second question is the only one that really matters.
If you want to navigate among molecules on your own, the starting point is the guide to cosmetic ingredients.
What I really think
The INCI is a valuable tool, as long as you use it for what it is. It tells you which raw materials were used. It doesn't tell you how much of them, in what form, how they were processed, or within which system.
The practical consequence is just one: an ingredient list is not enough to make a decision, and anyone who presents it as proof is oversimplifying. This applies to someone selling a dupe by saying it's identical, and it also applies to someone selling an expensive product by showing you three grand-sounding names on the cover.
Free 15-minute consultation with the founder
Have a label in your hands and don't know how to interpret it, or want to understand whether a product makes sense for your skin? Let's look at it together.
Elisa Avalle is the founder of LeLang Skin Care, specializing in dermocosmetics at the Universitat de Barcelona. Formulated in the Langhe for Italian pharmacies.
Where to continue
01 What happens before an active ingredient goes into a cream
02 Guide to cosmetic ingredients
03 Hyaluronic acid: high or low molecular weight
04 Why cream pills or leaves skin greasy
