"May contain" vs the ingredients list: what each really means
The ingredients list and the 'may contain' line do two different jobs. Knowing which is which is the difference between a confident decision and a guess.
Two different statements sit on a food label, and people routinely confuse them. Getting them straight is the single most useful label-reading habit.
The ingredients list is the law
Everything deliberately put into the product appears here, by law, in descending order of weight. The 14 major UK allergens are emphasised, usually in bold, every time they appear as an ingredient. This is the part you can trust: if your allergen is a deliberate ingredient, it will be here, and it will stand out.
“May contain” is a voluntary warning
“May contain”, “made in a factory that also handles”, and similar lines are precautionary allergen labelling. They describe the risk of cross-contamination during manufacture, not the recipe. Crucially, they are voluntary and unregulated: brands apply them inconsistently, and many over-use them, which dilutes their value.
That has two consequences. A product that carries the warning is not necessarily more dangerous than one that doesn’t, and a product without the warning is not guaranteed free of traces. The absence of a “may contain” line tells you very little.
How to use them together
Read the ingredients list first and let it make the clear decisions: allergen present as an ingredient means put it back. Then treat any “may contain” line as a personal risk call - one you make consistently, the same way every time, and that everyone who shops for you applies too. It is information to weigh, never a safety guarantee.
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Common questions
Is 'may contain' required by law?
No. Precautionary allergen labelling like 'may contain' is voluntary in the UK. The ingredients list, and the emphasis of the 14 major allergens within it, is what the law requires.
Can a product with no 'may contain' still cause a reaction?
Yes. Because the warning is voluntary, its absence is not a guarantee of safety. The ingredients list is the part you can rely on.