What an allergen label promises, and what it does not

Two statements can appear near the bottom of an American food label. They look like a pair, printed in the same place in the same size, and people read them as two strengths of the same warning.

They are not related at all. One is written into federal statute with the wording specified. The other is not mentioned in that statute anywhere.

What “Contains” is

The law names nine major food allergens: milk, egg, fish, crustacean shellfish, tree nuts, wheat, peanuts, soybeans and sesame.

If a food contains one, the statute gives the manufacturer exactly two ways to say so. Either the word “Contains” followed by the food source appears immediately after or adjacent to the ingredient list, in type no smaller than the list itself. Or the food source is named in parentheses inside the list, after the ingredient’s usual name.

That is a real, enforceable requirement with the typography specified. A product with milk protein in it cannot leave you to work that out from the word Casein or Whey, and a product with wheat protein cannot hide behind Hydrolysed wheat protein. This is the strongest guarantee on the whole packet, and it is why the back of the pack beats the front in almost every other argument on this site.

What “may contain” is not

Search the same subsection for the words “advisory” or “may contain” and they are not there. Not defined loosely, not defined weakly. Absent.

Three consequences follow, and they are the reason this page exists.

No threshold sits behind it. Nothing in the statute says how much cross-contact triggers the phrase, because the statute does not address the phrase. Two manufacturers with identical production lines can reach opposite decisions and both be within the law.

Its absence guarantees nothing. A packet with no advisory statement has not told you the line is clean. It has told you the manufacturer did not print a sentence they were never required to print.

Its presence is not a measurement. It is a judgement made by a company weighing its own risk, and you cannot read the size of the risk out of the wording. May contain, made in a facility that also processes, not suitable for and the rest are not a scale, however much they read like one.

The duty runs the other way

This is the part that reframes it. The regulations do not require a warning, but they do require prevention.

Manufacturers operating under the preventive controls rule must have allergen controls covering, in the regulation’s words, “ensuring protection of food from allergen cross-contact, including during storage, handling, and use”, and ensuring the finished food is correctly labelled.

So the legal obligation is to control the cross-contact, not to warn you about it. An advisory statement is what a company adds when it decides the control is not complete enough to stay silent. That is genuinely informative, and it is also entirely their call.

The exemption almost nobody knows

The definition of a major food allergen carves out one thing: highly refined oil derived from one of the nine, and any ingredient derived from that oil.

So a highly refined peanut oil is not a major food allergen in the legal sense, and a product containing it need not carry a peanut declaration. The protein is what causes the reaction and refining removes it, which is the reasoning. Whether that reasoning applies to you at your level of sensitivity is a question for the person who diagnosed you, not for a website and not for a scanner.

There is also a petition route: a manufacturer can ask for a specific ingredient to be exempted, carrying the burden of showing with scientific evidence that it does not provoke a reaction.

How this changes a shopping trip

Read the “Contains” line first. It is short, it is mandatory, and it catches an allergen under every name it travels under, including the ones designed to be technical rather than concealing, like the caseinates or the lecithins that Soy lecithin is filed under.

Then read the ingredient list, for the things allergen law does not cover: an animal ingredient, an additive you are avoiding, a sensitivity that is not one of the nine.

Then treat any advisory statement as information about the manufacturer rather than about the food. It tells you they thought about it and reached a conclusion. It does not tell you what is in the packet, and no amount of careful reading will make it do so.

The wider picture of reading a label with an allergy, including the names to learn, is on the page for food allergies.