Can a cosmetic leave an ingredient off the label?

For most people the ingredient list is a curiosity. For someone with a contact allergy it is the whole safety system, and it is worth knowing precisely how complete it is required to be.

The rule is strong

Every package “shall bear a declaration of the name of each ingredient in descending order of predominance”, and that declaration must “appear with such prominence and conspicuousness as to render it likely to be read and understood by ordinary individuals under normal conditions of purchase”.

Order of predominance is the part that does quiet work. It is why position in the list carries information even though no percentages are given.

And then three doors are left open

Fragrance and flavour. The same sentence that requires each ingredient by name adds “except that fragrance or flavor may be listed as fragrance or flavor”. One word can stand for a composition of dozens.

Trade secret. Where an ingredient “is accepted by the Food and Drug Administration as exempt from public disclosure pursuant to the procedure established in § 720.8(a) of this chapter, in lieu of label declaration of identity the phrase “and other ingredients” may be used at the end of the ingredient declaration.”

That is not a loophole taken unilaterally. There is a procedure, and a request “should contain a full statement, in a well-organized format, of the factual and legal grounds” for it. But the outcome, from where you are standing in a shop, is a phrase instead of a name.

Incidental ingredients. The least known and, for an allergy, often the most consequential: the rule “do not require the declaration of incidental ingredients that are present in a cosmetic at insignificant levels and that have no technical or functional effect in the cosmetic.”

Two categories qualify. Substances “present by reason of having been incorporated into the cosmetic as an ingredient of another cosmetic ingredient”, and processing aids.

What to do with this if you react to things

Treat the list as strong evidence rather than proof. If a product with a clean-looking list still causes a reaction, the three doors above are the first place to look, and the second is that the reaction may be to something present under a name you did not recognise.

Limonene is a common example of the first door, since it is frequently part of a fragrance rather than a separate entry. Cocamidopropyl betaine is an example of the opposite problem: it is always named, and it is still missed because the name means nothing to most readers.

Where the rules differ

The fragrance door is narrower in the EU, where certain fragrance allergens have to be named individually above a threshold. That divergence is worth understanding on its own terms, and the comparison is here.