"May contain nuts"
Three words that appear on menus, packaging, and websites, and mean something slightly different in each context. For people managing food allergies, it affects the decisions they make about what they can and cannot safely eat.
This article explains what the phrase means in different contexts, what it does not tell you, and how to respond to it.
What "may contain" means technically
"May contain" is a form of precautionary allergen labelling, often referred to as PAL. It is a statement that a product or dish may contain trace amounts of an allergen due to the risk of cross-contamination during preparation.
In plain terms: the allergen is not in the recipe, but the kitchen cannot guarantee it is not in the dish.
On packaged food, precautionary allergen labelling is voluntary in most jurisdictions including the UK, EU, and US. There is no legal requirement for a manufacturer to declare a cross-contamination risk. South Korea is one of the few exceptions, where PAL is legally mandated. Everywhere else, when it appears on packaging, it means the producer has assessed the risk and chosen to disclose it. As of March 2026, the UK Food Standards Agency is actively reviewing whether that should change, as part of international discussions on standardising allergen thresholds.
On restaurant menus, there is also no legal requirement for restaurants to use "may contain" labelling. When a restaurant uses it, it is a voluntary disclosure. Some use it precisely and specifically. Others use it as a catch-all, applied broadly to the entire menu, regardless of whether they have actually assessed the specific risk for each dish.
What it signals in a restaurant
When a restaurant menu says "may contain [allergen]" on a dish, it could mean a few things:
The warning has been passed through from a single ingredient's packaging. If a supplier labels an ingredient with "may contain…", some kitchens carry that through to the menu as a precaution. In that case the risk originates in the supply chain, not necessarily in the kitchen with how the dish is prepared.
The kitchen uses shared equipment such as a fryer, prep surface or set of utensils that also comes into contact with the named allergen. The dish itself does not contain the allergen as an ingredient, but trace contact is possible. In this scenario, the kitchen has assessed the cross-contamination risk and is disclosing it.
The kitchen has not fully assessed the risk, but knows that it handles the allergen somewhere in its operation, and has added "may contain" as a blanket precaution across some or all dishes. This is less useful because it tells you there is some risk somewhere but does not tell you how significant or specific it is.
The phrase on its own does not distinguish between these. That is why a follow-up question is useful. More on that in our guide to the specific questions that can help identify which of these you are dealing with, and what to listen for in the answers.
What it does not tell you
"May contain" does not tell you how significant the risk is.
For example, a restaurant that uses a shared fryer to prepare a dish is a meaningfully different risk from an allergen that is used in one dish as a topping.
Both kitchens might put "may contain" on their menus. The phrase treats both the same. The actual risk significantly more in the first scenario.
It does not tell you whether the kitchen has a system for managing cross-contamination, or whether the disclosure is the result of an actual risk assessment or a precautionary habit.
It does not tell you whether the risk is relevant to your specific allergy. Trace exposure matters very differently depending on whether you have a severe anaphylactic food allergy, a milder sensitivity, or a food intolerance.
The difference between packaged food and a restaurant menu
When "may contain" appears on a packaged food product, it has a specific and contextualised meaning. The manufacturer is disclosing a cross-contamination risk that exists in the production facility, assessed against production processes.
When it appears on a restaurant menu, it exists in a different context entirely. The production is live, in a kitchen, varying from service to service. The risk may change depending on which dishes are ordered that day, how busy the service is, and which staff are working.
This is not to say the restaurant menu use is less careful. Some restaurants use it very precisely. But it is worth understanding that the same phrase in two different contexts does not carry identical meaning.
Food allergy versus intolerance
The relevance of a "may contain" statement depends significantly on whether you are managing a food allergy or a food intolerance.
For a food allergy, an immune-mediated response that can be triggered by very small amounts, trace cross-contamination is a genuine and serious risk. A "may contain nuts" statement on a menu is relevant information for someone with a nut allergy, even if the dish contains no intentional nut ingredient.
For a food intolerance, typically a digestive response that is dose-dependent, trace contact is less significant. A small amount of the trigger is unlikely to cause a serious reaction, even if it may cause some discomfort in larger quantities. Many people with lactose intolerance, for example, can eat dishes prepared in a kitchen that handles dairy without any issue.
If you are unsure which category you are in (allergy versus intolerance) it is worth speaking to a healthcare provider about your specific condition and what level of exposure is clinically significant for you.
The follow-up question
If a menu says "may contain" or a server mentions a cross-contamination risk, this question is the most useful one to ask:
"What specifically is the risk; is it a shared fryer, same surfaces, or is the allergen used in other dishes in the kitchen?"
A specific answer gives you something to work with, a concrete risk you can assess. Vague answers, on the other hand, do not give you enough to make a confident decision. In that case, ask more specifically, or consider ordering something simpler where the risk is easier to assess.