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Allergen Cross-Contact Prevention

'May Contain' Warnings: When to Use Them & Legal Position

'May Contain' Warnings: When to Use Them & the Legal Position

Precautionary allergen labelling, commonly known as "may contain" warnings, is one of the most contentious areas of allergen management. These warnings are voluntary, not required by law, and are intended for situations where a genuine risk of cross-contact exists despite all reasonable precautions. In practice, they are frequently overused as a blanket liability shield, which frustrates consumers with allergies, erodes trust, and does not actually protect the business from legal liability if the underlying risk assessment is inadequate. This article explains when "may contain" warnings are appropriate, when they are not, and what the legal position actually is.

Key takeaways

"May contain" warnings are voluntary and do not provide legal protection without documented controls
Only use PAL after all reasonable cross-contact controls have been implemented and a residual risk remains
Blanket "may contain all allergens" warnings are not compliant and suggest no risk assessment exists
"May contain" for allergens that are actual ingredients is wrong. Declare them in the ingredients list
A conversation with the customer is often more effective than a printed warning

The Legal Position: Voluntary, Not a Defence

Precautionary allergen labelling (PAL) is not required by UK or EU food law. It is voluntary and sits outside the mandatory allergen declaration framework of the Food Information Regulations 2014. The FSA's position is clear: PAL should only be used as a last resort after all reasonable measures have been taken to control cross-contact. A "may contain" warning is not a substitute for good manufacturing practice. Critically, a "may contain" warning does not provide legal protection against prosecution if a customer suffers a reaction. If an enforcement officer or court determines that reasonable cross-contact controls were not in place, the warning itself will not help. The business must demonstrate due diligence: that it took all reasonable precautions and exercised all due diligence to avoid the offence. This means the "may contain" warning must be supported by a documented risk assessment showing what controls are in place and why a residual risk remains.

When "May Contain" Warnings Are Appropriate

A legitimate "may contain" warning covers situations where you have identified a genuine cross-contact risk through a risk assessment, you have implemented all reasonable control measures (separation, dedicated equipment, validated cleaning, workflow controls), a residual risk still exists that cannot be eliminated without disproportionate measures, and the risk is specific and quantified, not vague or assumed. Examples include a bakery that produces nut-containing and nut-free products on different production lines in the same facility, with validated cleaning between runs, but where airborne nut dust poses a residual risk. Or a restaurant that has a dedicated allergen-free prep area but shares a ventilation system with the main kitchen where nut dishes are prepared. In both cases, the business has done everything reasonable and the "may contain" warning communicates a genuine residual risk to help the consumer make an informed decision.

When "May Contain" Warnings Are Not Appropriate

Blanket "may contain all 14 allergens" warnings on every product are not acceptable. They provide no useful information to consumers and suggest that no risk assessment has been conducted. If every product "may contain" every allergen, the consumer has no basis for making a safe choice. Similarly, using "may contain" to cover allergens that are actually present as ingredients is wrong. If a dish contains milk, declare it as an ingredient. "May contain milk" is not a substitute for "Contains milk." Using "may contain" for allergens present in other products made in the same kitchen, without any documented controls, is also problematic. If you know cross-contact is occurring and you have not taken steps to prevent it, a warning does not demonstrate due diligence. It demonstrates awareness of a problem you have not addressed. The FSA has stated that overuse of PAL is a significant concern because it limits food choices for consumers with allergies and undermines trust in warnings that are genuinely warranted.
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Communicating Cross-Contact Risk Without Overusing PAL

There are alternatives to blanket "may contain" warnings that communicate risk more effectively. For loose food in a restaurant or cafe, you can train staff to explain cross-contact risks honestly when a customer discloses an allergy. "Our kitchen handles nuts and we take precautions, but I cannot guarantee zero contact" is more useful than a printed "may contain all allergens" disclaimer. On menus, you can include a statement such as "Our kitchen uses all 14 allergens. Please speak to a team member about your specific allergy and we will advise on the safest options." This shifts the communication from a warning to a conversation, which is more effective at preventing reactions. For PPDS and prepacked food, only apply "may contain" warnings to specific, documented risks supported by your risk assessment. This keeps the warnings meaningful and trustworthy.

What to do next

Audit all current "may contain" warnings

Review every product or menu item that carries a precautionary warning. Check whether each one is supported by a documented risk assessment with specific controls.

Remove blanket warnings and replace with specific ones

If you currently use "may contain all allergens" on everything, replace with specific, risk-assessed warnings only where a genuine residual risk exists after controls are in place.

Train staff on allergen conversations

Equip front-of-house staff to have honest conversations about cross-contact risk. Provide scripts or talking points for common allergen queries.

Common mistakes to avoid

Mistake
Using "may contain" as a substitute for allergen controls
Instead
A warning without underlying controls is not due diligence. Implement physical separation, cleaning, and workflow controls first. Only then consider PAL for residual risks.
Mistake
Applying "may contain" to allergens that are actual ingredients
Instead
If an allergen is deliberately added to a product, it must be declared in the ingredients list, not in a precautionary warning.

Frequently asked questions

Is there a legal threshold for allergen cross-contact?

UK law does not define a safe threshold for allergen cross-contact. Any amount of an allergen can potentially cause a reaction in a sensitive individual. This is why controls must aim to eliminate cross-contact, not just reduce it to a level you consider acceptable.

Can a customer sue me if they react to a "may contain" product?

A "may contain" warning does not prevent a claim. If a court finds that your controls were inadequate and the warning was used as a substitute for proper management, you could still be liable. The warning supports your case only if it was the final layer after all reasonable precautions.

Should I put "may contain" on my menu?

A general kitchen statement ("Our kitchen handles all 14 allergens") is helpful context. Specific "may contain" warnings on individual dishes should be reserved for documented residual risks. Avoid blanket warnings that apply to everything.

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Common Allergen Labelling Mistakes & How to Avoid Them

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Communicating Allergens to Customers: Verbal, Written & Digital

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