What "may contain" really means on a food label

Updated 2026-07-21

"May contain nuts." "Made in a facility that also processes milk." "Made on shared equipment with wheat." These precautionary allergen labels (PAL) are everywhere, and they cause a lot of confusion, because they do not mean what most people assume. This is a sourced guide to what they actually tell you.

This is general information, not medical advice. How to treat "may contain" for your own allergy is a decision for you and your allergist.

The key fact: they are voluntary

Unlike the allergens a maker deliberately puts in a product (which the law requires to be declared), precautionary "may contain" statements are voluntary and not regulated. In the UK, the US, the EU and Australia, the law does not require these warnings and does not govern how they are worded. A manufacturer chooses whether to add one, and what to say.

That is why you see so many different phrasings: "may contain", "not suitable for", "made in a facility that also handles", "made on shared equipment with". They are not different levels of risk. They are just different wordings for the same unregulated idea, possible cross-contact.

They are not a measure of risk

This is the part that trips people up. The UK Food Standards Agency is explicit that the presence or absence of a precautionary label is not intended to be an absolute indicator of risk or safety, only a starting point for you to consider your own risk.

Two consequences follow:

• No warning does not mean no risk. Because PAL is voluntary, a product with real cross-contact can carry no warning at all. Absence of "may contain" is not a guarantee the allergen is absent.
• A warning does not mean a set amount. There is no legal threshold behind the words. One product's "may contain" might reflect genuine shared-line contact; another's might be pure caution over something very unlikely. Identical warnings can carry very different real risk.

The Food Allergy Research & Education (FARE) blog makes the same point: precautionary labels are inconsistent and not a reliable guide to how much allergen, if any, is present.

Why overuse is a problem

Because it is free and protects the manufacturer, "may contain" is often applied very broadly. The FSA notes that excessive use of precautionary labels can unnecessarily limit choice and devalue the warning, which can push some people toward risk-taking (ignoring the labels entirely). Neither outcome is good: allergic families end up either eating less safely or eating far fewer foods than they need to.

The attempt to fix it: thresholds and VITAL

There is work to put science behind the warnings. The Allergen Bureau's VITAL (Voluntary Incidental Trace Allergen Labelling) program gives food makers a standardised way to assess cross-contact against reference doses, amounts below which a reaction is unlikely for most allergic people, so a "may contain" is only used when it is actually warranted. Regulators including the FSA have looked at threshold-based approaches. But VITAL is still voluntary, so on any given pack you usually cannot tell whether a threshold method was used.

So what should you do?

Because the labels are not standardised, how you treat them has to be personal and medical, not a rule you read off the pack:

• For a severe or anaphylactic allergy, many allergists advise treating "may contain" as unsafe. Ask yours what applies to you.
• For a milder sensitivity, your allergist may agree some precautionary products are acceptable.
• Either way, the warning is a prompt to apply your own plan, not a number you can trust.

How AllergyLens handles it

AllergyLens reads the "may contain" section of a label separately from the ingredients, and by default treats traces as unsafe (red) for every watched allergen, the safety-first assumption. If your allergist agrees trace exposure is tolerable for a specific allergen, you can relax just that one to a caution (amber) in the profile editor. It never silently downgrades a warning for you.