What Is The Most Common Food Allergy

Ask ten people this question and you’ll get ten different answers. Milk? Peanuts? Shellfish?

Here’s the thing: the honest answer is, it depends who you’re talking about.

A two-year-old and a 42-year-old will likely be allergic to completely different foods. And the allergy that is the most prevalent is not the same as the one that is the most dangerous.

Let me break it down properly, without the myths.

The short answer

In UK children, the most common food allergy is cow’s milk, closely followed by egg and then peanut.

In UK adults, it is a very different picture. Peanut and tree nuts lead the list, with pollen-food syndrome (reactions to certain raw fruits and vegetables) sitting quietly in the background as one of the sneakier adult allergies.

That is the 10-second version. Now let’s unpack it properly, because if you run a food business or handle food for a living, the detail really matters.

The UK 14 named allergens (and why they matter legally)

Before we rank anything, you need to know the legal list.

Under UK food information law, there are 14 named allergens that must be declared by food businesses. Not 13. Not 15. Fourteen. They are:

• Cereals containing gluten (wheat, rye, barley, oats and their hybrids)
• Crustaceans (prawns, crab, lobster)
• Eggs
• Fish
• Peanuts
• Soybeans
• Milk
• Tree nuts (almonds, hazelnuts, walnuts, cashews, pecans, Brazil nuts, pistachios, macadamia)
• Celery (and celeriac)
• Mustard
• Sesame
• Sulphur dioxide and sulphites (at more than 10mg/kg)
• Lupin
• Molluscs (mussels, oysters, squid, snails)

Important: this legal list is not the same as the “most common” list. It exists because these 14 are the ones most likely to cause severe allergic reactions across the UK population, and therefore the ones regulators require you to declare.

This is the list behind Natasha’s Law, which came into force on 1 October 2021 and covers food that is Prepacked for Direct Sale (PPDS). If you make a sandwich on-site and pop it in a chiller for a customer to pick up, the full ingredient list with the 14 allergens emphasised in bold must be on the pack.

Most common vs most severe, not the same thing

This is where a lot of articles get muddled.

Most common = how many people have the allergy.

Most severe = how bad the reaction tends to be when it happens.

Cow’s milk allergy is extremely common in small children, but the vast majority of reactions are not life-threatening and most children outgrow it by school age.

Peanut, tree nut, sesame and shellfish allergies are less common overall, but they are far more likely to trigger anaphylaxis, and they tend to be lifelong.

You need both lenses to make sense of the question.

The most common food allergies in UK children

Childhood food allergy is what drives most of the headline statistics, because prevalence is highest in the early years and drops with age.

A 2024 analysis in The Lancet Public Health looked at clinically recorded food allergy in England and found the prevalence was 4.0% in children under five, falling to 2.4% in school-age children and just 0.7% in adults (Turner et al., 2024).

In under-5s, the top three are fairly consistent:

1. Cow’s milk, the most common food allergy in babies and toddlers
2. Egg, usually presents in infancy, often alongside eczema
3. Peanut, the one parents fear most, and with good reason

The good news? Many children outgrow cow’s milk and egg allergies before they start school. Peanut and tree nut allergies, on the other hand, are usually for life.

The most common food allergies in UK adults

Adult food allergy is a different animal entirely.

The Food Standards Agency’s Patterns and Prevalence of Adult Food Allergy (PAFA) report, published in May 2024, estimated that around 6% of UK adults, roughly 2.4 million people, have a clinically confirmed food allergy. And crucially, about half of those allergies developed in adulthood rather than childhood (FSA, 2024).

The most common adult food allergies in the UK are:

• Peanut
• Tree nuts (hazelnut, walnut and almond in particular)
• Pollen-food syndrome (reactions to raw apple, peach, kiwi fruit and other fresh fruits, celery, carrot)

That middle one surprises people. Pollen-food syndrome, sometimes called oral allergy syndrome, affects roughly 2% of UK adults, and up to two thirds of people who are sensitised to birch pollen can develop it. Symptoms usually stay in the mouth and throat, but occasionally they go systemic (BSACI, 2022).

If your hay fever seems to make raw apple itch, that is why.

What are the “big 5” or “big 8” food allergies?

This comes up a lot in searches, so it is worth clearing up.

The “big 8” is an older American framing. It refers to milk, eggs, peanuts, tree nuts, soy, wheat, fish and shellfish, the eight allergens that together cause roughly 90% of food allergic reactions in the United States.

The “big 5” is a looser, informal shorthand for the five most common globally: milk, eggs, peanuts, tree nuts and shellfish.

In the UK, we don’t really use these terms. We use the 14 named allergens list instead, which is broader and built around our own legal labelling rules.

What’s the worst food allergy to have?

There is no single answer, but by most measures peanut allergy is the one clinicians watch most closely in children and young adults.

Peanut reactions are more likely to progress to anaphylaxis than most other food allergies, they rarely resolve, and the allergen is hidden in a huge range of products. Tree nut, sesame and shellfish allergies sit in the same bracket.

If you suspect you or a family member has a food allergy, please speak to your GP. They can refer you to an NHS allergy specialist for proper testing. Don’t rely on at-home IgG kits or elimination diets you’ve read about online, they are not reliable for diagnosis.

Which allergens trip food businesses up most often?

This is the bit competitor articles miss entirely.

From what we see in the training we deliver to food businesses up and down the country, the same few allergens cause the same few problems again and again.

Milk and egg, because they hide in everything. Glazes, batters, brioche buns, mashed potato, pastry, ice cream, some “dairy-free” products that still contain egg, and endless breaded items.

Gluten, not just in obvious bread and pasta. Soy sauce, some stock cubes, malt vinegar, barley in beer, cheap sausages, tempura batter, even some chips that have been coated.

Sesame, under-recognised and increasingly common. Hummus, tahini, some breads, burger buns, many Asian dressings.

Celery and mustard, the stealth ingredients. They turn up in stock, gravy, sauces, mayo, marinades and seasoning blends, and staff often don’t realise.

Sulphites, in dried fruit, wine, some processed meats and certain fruit juices. People forget they count.

The single biggest cause of a failed allergen check is not a missing menu disclaimer. It is a team member who genuinely doesn’t know which products in the kitchen contain which allergen. That is a training gap, not an attitude problem.

A quick word on “may contain” labels

One of the things the FSA has flagged in its research is that many consumers with food allergy have lost trust in precautionary “may contain” labelling. Some studies show substantial numbers of allergic consumers ignore these warnings altogether, because they feel vague or over-applied (FSA, 2023).

That is worth knowing if you are writing labels. If “may contain” appears on a product that genuinely has no cross-contact risk, you are training customers to dismiss it on products where the risk is real.

Training your team on the 14 allergens

If you run a kitchen, a café, a childminding setup or a catering operation, the 14 allergens aren’t just trivia. Every member of staff who touches food needs to know what they are, where they hide, and what to do when a customer asks.

Our Allergy Awareness course walks your team through the 14, the law, cross-contamination, how to handle a customer query, and what an anaphylactic reaction looks like if the worst happens. It’s CPD-accredited, 100% online, and learners get an instant digital certificate on passing. For businesses with 10+ learners, bulk discounts kick in automatically through the group management portal, so you can assign courses to your whole team and track completion in real time.