Food Allergies: How to Read Labels and Spot Hidden Ingredients
Food allergens hide behind dozens of technical names on ingredient lists. Here is what each of the 14 major allergens looks like on a label, and what to do when you are not sure.
Why labels are confusing
Food manufacturers are legally required to declare the 14 major allergens under EU and UK law. But the way they declare them varies. An allergen might appear in bold in the ingredients list, in a separate "Contains" statement, or in a "May contain" advisory. Some names are obvious. Many are not. Casein, whey, and lactalbumin are all milk proteins. Albumin and lysozyme are egg proteins. Groundnut oil and arachis oil are peanut. Knowing the technical synonyms is essential for anyone managing a food allergy.
The 14 major allergens
UK and EU law requires the following 14 allergens to be clearly indicated on pre-packaged food labels: milk, eggs, peanuts, tree nuts (almonds, cashews, walnuts, pecans, pistachios, Brazil nuts, hazelnuts, macadamia), cereals containing gluten (wheat, rye, barley, oats), soya, fish, crustaceans (prawns, crab, lobster), celery, mustard, sesame, lupin, molluscs (mussels, oysters, squid), and sulphur dioxide and sulphites. Each has a family of alternative names that manufacturers may use.
May contain warnings
"May contain" or "made in a factory that also handles" statements are voluntary in the UK and EU, not legally required. This means their absence does not guarantee a product is free from cross-contamination. Some manufacturers use them consistently; others do not. If you have a severe allergy, treat a product with no advisory as potentially unverified rather than as guaranteed safe. The Food Standards Agency is reviewing the use of precautionary allergen labelling.
Eating out and ordering in
Pre-packaged foods must declare allergens on the label. Food sold loose, in restaurants, or in takeaways must also declare allergens, but via a different route. Allergy information can be provided verbally, on a menu, on a chalkboard, or on request. Since Natasha's Law came into force in October 2021, food packaged on the same premises where it is sold (such as sandwiches made in a cafe) must also carry full ingredient and allergen labelling.
Practical tips for managing allergies
Build a habit of reading the full ingredients list, not just the allergen summary box. The summary may be incomplete or may not reflect a formula change. If you have a severe allergy, carry your prescribed medication (adrenaline auto-injector) at all times. Register with your GP and ask for a referral to an NHS allergy clinic for formal testing and management advice. Use the Allergen Checker tool on ProductSafer to see every name your specific allergen can appear under on a label.
Cross-reactivity between allergens
Some allergens share similar proteins, which can cause reactions across related foods. This is called cross-reactivity. People allergic to peanuts have a higher chance of reacting to lupin, another legume. Birch pollen allergy is associated with oral allergy syndrome when eating apples, pears, and stone fruits. Shellfish and mollusc allergy sometimes overlap. Milk allergy does not always mean beef allergy, but cross-reactivity has been documented. Your allergist can test for cross-reactive sensitivities and advise on what to avoid.