Food allergy: diagnosis and management

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The UK has some of the highest allergy rates in the world, with 39% of children and 30% of adults affected. Despite this, allergic disease remains significantly under-resourced in the NHS.

Many GPs begin their careers with little or no formal training in allergy, and patients frequently experience delays in diagnosis. Access to specialist services varies considerably across the country, creating a postcode lottery and resulting in inconsistent standards of care.

According to the National Allergy Strategy, launched in April, all healthcare professionals should receive core and ongoing education in allergy, including food allergy, hay fever and rhinitis. This includes community pharmacists and their teams, who should be equipped to support patient self-care and improve access to effective treatments, including OTC antihistamines and intranasal corticosteroids.

Food allergies

Food allergy affects around 4% of pre-school children, 2.4% of school-aged children and 1-2% of adults in this country. Although many food allergies are first diagnosed during childhood, research published in the British Medical Journal in 2024 found that around half of adults with food allergies developed their allergy after the age of 35 years.

The most common food allergens in the UK are celery, cereals containing gluten (wheat, rye, barley and oats), crustaceans, eggs, fish, lupin, milk, molluscs, mustard, peanuts, sesame, soybeans, sulphur dioxide and sulphites (above 10 ppm), and tree nuts.

However, changes in diet and lifestyle have contributed to increasing numbers of allergies to other foods. These include plant proteins such as legumes, garden peas and mange tout, as well as goat’s milk, sheep’s milk, kiwi fruit, apples, and beehive products.

Research using data from the European Anaphylaxis Registry, published in June 2025, found that cashew nuts are now the leading cause of nut-induced anaphylaxis in children across Europe, overtaking peanuts. The study also identified almonds as an unexpected cause of anaphylaxis in adults.

Cow’s milk allergy 

Cow’s milk allergy is one of the most common food allergies in childhood. According to Allergy UK, it affects approximately 7% of infants under one year of age, although most children eventually outgrow the condition.

Symptoms depend on whether or not the allergy is mediated by immunoglobulin E (IgE) antibodies. Reactions may therefore be classified as either IgE-mediated (immediate) or non-IgE-mediated (delayed). Cow’s milk allergy in older children and adults is generally associated with a higher risk of severe reactions.

When babies and children with IgE-mediated cow’s milk allergy consume milk or dairy products, they may develop one or more of the following symptoms:

• Urticaria (hives or nettle rash)
• Swelling of the lips, face or eyelids
• Vomiting
• Breathing difficulties
• Floppiness or collapse
• Anaphylaxis.

Skin contact with milk may also trigger dermatological reactions. In most cases, breastfed infants with IgE-mediated cow’s milk allergy do not develop symptoms when their mother consumes dairy products.

Babies and children with non-IgE-mediated cow’s milk allergy may develop symptoms several hours after consuming milk or dairy products. These may include:

• Itchy skin
• Eczema
• Abdominal pain
• Diarrhoea
• Blood or mucus in the stools
• Constipation
• Refusal of feeds
• Vomiting
• Poor growth
• Persistent irritability and unsettled behaviour.

These symptoms may also occur in breastfed infants when the mother consumes milk or dairy products.

Allergy versus intolerance

Many people are unclear about the difference between a food allergy and a food intolerance, particularly in relation to cow’s milk and dairy products. A food allergy involves the immune system, whereas a food intolerance does not.

In food allergy, the immune system mistakenly identifies proteins within a food as harmful and triggers an inflammatory response. This reaction causes allergy symptoms and means that the offending food must usually be avoided completely to prevent further reactions.

Food intolerance occurs when the digestive system is unable to digest, absorb or process a particular food effectively. This may result from an enzyme deficiency, such as lactase deficiency, or sensitivity to naturally occurring food chemicals or additives.

Unlike food allergy, some people with food intolerance can tolerate small amounts of the trigger food or consume it in specific forms. For example, yoghurt and hard cheeses generally contain less lactose than milk. People with lactose intolerance may also benefit from lactase enzyme supplements when consuming lactose-containing foods.

Symptoms of food intolerance often occur several hours after eating or drinking the trigger substance and may include:

• Bloating
• Nausea
• Diarrhoea
• Abdominal pain.

These symptoms can closely resemble those of non-IgE-mediated cow’s milk allergy, which can make diagnosis challenging.

Diagnosing food allergies

According to an Ipsos poll published in December 2025, one in four people in Britain reported having a food or drink allergy or intolerance. However, fewer than half (49%) of those with allergies and only 31% of those with food intolerances had received a clinical diagnosis from a healthcare professional.

As a result, many people are self-diagnosing by researching symptoms online or using home testing kits. This may lead to unnecessary dietary restrictions, delayed diagnosis or inappropriate management.

If a patient presents with suspected food allergy or intolerance, pharmacy teams should encourage them to consult their GP. Formal diagnosis is essential, particularly as allergic reactions can be severe and, in some cases, fatal.

Patients should be referred even if symptoms appear mild, as future allergic reactions may be more severe. Assessment of suspected food intolerance is also important to ensure foods are not excluded unnecessarily and to identify alternative causes of symptoms, such as irritable bowel syndrome.

In most cases of suspected food allergy, patients are referred to a specialist allergy service for further investigation. Diagnostic assessment may include blood tests, skin-prick testing and oral food challenge testing. An exclusion diet may help identify non-IgE-mediated allergy or food intolerance. However, this should only be undertaken under the supervision of a dietitian or specialist clinician.

Patients diagnosed with a food allergy will usually need to eliminate the relevant allergen completely from their diet. For breastfed infants with cow’s milk allergy, this may also require the mother to exclude all milk and dairy products from her own diet.

Avoidance advice

Once a food allergy has developed, future exposure to the same allergen is likely to trigger further reactions. Patients therefore need clear advice on allergen avoidance, ideally supported by a dietitian with expertise in food allergy management.

In most cases, complete avoidance of the trigger food is required. However, some individuals may tolerate small amounts of certain allergens, and in some cases cooking or processing a food may reduce its allergenicity.

Patients should be advised to read food labels carefully every time they purchase a product, even if they have consumed it previously. Manufacturers frequently change recipes and ingredients, which may alter allergen content.

The 14 major food allergens recognised in UK legislation, including cow’s milk, must be clearly identified on food labels, typically with bold type. Patients should understand how to identify these allergens and recognise alternative ingredient names where relevant.

Restaurants, cafes, hotels, takeaways and other food businesses are legally required to provide information about major allergens. Nevertheless, patients should be encouraged to discuss their allergy directly with staff and ask about the potential risk of cross-contamination.

Infants who are bottle-fed and have cow’s milk allergy will usually require an extensively hydrolysed formula. In these products, cow’s milk proteins have been broken down into very small fragments that are less likely to trigger an allergic response.

If an extensively hydrolysed formula is not tolerated or accepted, an amino acid-based formula may be required. These formulas are considered hypoallergenic and are suitable for infants with more severe allergy.

Dietetic support is important to ensure that babies and children continue to receive adequate nutrition for normal growth and development. Attention should be paid to nutrients such as calcium when dairy products are excluded from the diet.

As children grow older, healthcare professionals may consider the supervised reintroduction of the allergen to determine whether tolerance has developed. This should only be undertaken under the guidance of a specialist doctor or dietitian and should never be attempted without close professional supervision.

Management advice

Patients should ideally be reviewed annually by their GP or an allergy consultant, with repeat allergy testing to assess whether food allergies are improving or worsening. All patients with food allergy should have an up-to-date allergy management or action plan, and associated conditions, such as asthma, eczema or rhinitis, should be closely managed.

Patients, or their parents, guardians or carers, must be able to recognise acute allergy symptoms, particularly severe reactions that require urgent medical attention.

Mild to moderate food allergy symptoms, such as an itchy red rash, itchy mouth, abdominal pain or vomiting, should be treated with an antihistamine (tablet or liquid) as soon as possible. A non-sedating antihistamine, such as cetirizine or loratadine, is usually recommended, although chlorphenamine, a sedating antihistamine, may be prescribed for young babies.

Antihistamines should not be used instead of adrenaline if the allergic reaction is severe.

If allergy symptoms affect the airway (for example, throat tightness or difficulty swallowing), breathing (including wheezing or chest tightness) and/or circulation (e.g. dizziness or fainting), this indicates a severe allergic reaction (anaphylaxis).

The patient should lie flat with their legs raised, or sit slightly upright if breathing is difficult, but they should not stand. If they have an adrenaline autoinjector, it should be used without delay. The patient or carer should call 999 for an ambulance and state that the patient is experiencing an anaphylactic reaction.

If symptoms do not improve after five minutes, a second dose of adrenaline should be given. Medical observation in hospital is recommended following anaphylaxis, even if the patient appears to have recovered.

Adrenaline autoinjectors

According to the National Allergy Strategy, national guidelines recommend that people with food allergies who are at risk of anaphylaxis are prescribed two adrenaline autoinjectors. However, less than half of people with previous food-related anaphylaxis are prescribed these regularly, particularly in areas of socioeconomic deprivation.

In April 2026, research presented at the Royal College of Emergency Medicine conference identified fatal delays in administering life-saving adrenaline autoinjectors, such as EpiPen, during food-related anaphylaxis. In many cases, children did not receive sufficient adrenaline before cardiac arrest occurred – and some did not carry an adrenaline autoinjector at all.

Community pharmacists play an important role in ensuring patients, parents and carers carry adrenaline devices and understand how to use them. Most adrenaline autoinjectors are supplied through repeat prescriptions. Devices should be administered into the muscle in the middle of the outer thigh (upper leg), including through clothing. Different brands have slightly different instructions.

In July 2024, the updated NICE Quality Standard on anaphylaxis stated that people experiencing, or at risk of, anaphylaxis should be retrained on the safe and effective use of their adrenaline autoinjector each time the device is prescribed. Trainer devices and demonstration videos can be ordered by pharmacists and patients from manufacturers’ websites.

Adrenaline autoinjectors must be replaced when they have expired, or if the liquid visible through the device window becomes brown or contains particles. The solution should be clear and colourless.

Devices should be stored correctly in an insulated bag, as adrenaline is sensitive to light and may be damaged by extreme temperatures. Patients should be reminded to check the expiry dates of their adrenaline autoinjectors when collecting prescriptions. They can also register for expiry alert services through the relevant manufacturer’s website.

Research shows that some people delay using autoinjectors because of fear or uncertainty about needles, while young people may find the devices too bulky to carry.

In July 2025, EURneffy, an adrenaline nasal spray for anaphylaxis, was approved by the MHRA. EURneffy delivers adrenaline into one nostril. Patients should always carry two nasal sprays in case a second dose is required. The nasal spray is easy to store, relatively small, non-invasive and needle-free, and has a longer shelf life than adrenaline autoinjectors.

Community pharmacists should ensure that their pharmacy has in-date adrenaline supplies and adrenaline autoinjectors available. Community pharmacists can administer intramuscular adrenaline up to 1mg/ml to save a life during an anaphylactic emergency.

Adrenaline autoinjectors should not be used as a substitute for a complete anaphylaxis emergency pack. Pharmacists should be competent to draw up and administer adrenaline from ampoules using a syringe and needle. However, if an adrenaline autoinjector is the only available option, it can be used instead.