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Health condition · Clinically reviewed

Food allergies, from accurate diagnosis to adrenaline, Palforzia and omalizumab.

Immediate IgE reactions, delayed non-IgE patterns and everything in between. A specialist-led plan built around accurate testing, strict avoidance and modern treatment options.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK allergy clinician before publication.

  • 02

    Sourced from guidance

    Checked against BSACI, NICE CG116 and WAO standards you can see at the end.

  • 03

    Current for 2026

    Reflects Palforzia oral immunotherapy, omalizumab for food allergy and Natasha's Law labelling.

Key facts

Food allergies at a glance.

The essentials, in plain English - the patterns, the common triggers and how UK specialist services treat them.

  • What it is

    An immune-mediated adverse reaction to food proteins - distinct from intolerance, which is non-immune.

  • Types

    IgE-mediated (immediate), non-IgE-mediated (delayed) and mixed IgE plus non-IgE patterns each behave differently.

  • How common

    True allergy affects around 5% of adults and 8% of children in the UK, though self-reported rates are much higher.

  • Common triggers

    Cow's milk, egg, peanut, tree nuts, sesame, wheat, soy, fish, shellfish, kiwi and lupin.

  • Anaphylaxis

    The severe, life-threatening reaction - biphasic in 5 to 15% of cases and always needs adrenaline first.

  • UK context

    Natasha's Law (2021) requires full ingredient labelling on prepacked-for-direct-sale (PPDS) foods.

Why this guide matters

Accurate testing, strict avoidance, prepared for the worst.

Food allergies are far more often self-diagnosed than confirmed. A specialist-led approach protects patients from both under-treatment and needless restriction.

  • History drives everything

    Testing without a matched history produces false positives - a careful history is the diagnostic backbone.

  • Adrenaline is the only lifesaver

    For anaphylaxis, intramuscular adrenaline first - antihistamines and steroids are adjuncts, never substitutes.

  • Modern treatment has arrived

    Palforzia and omalizumab now sit alongside avoidance and adrenaline - specialist commissioned pathways matter.

How the diagnosis is made

From first reaction to a clear diagnosis.

The steps a UK allergist follows in line with BSACI Standards of Care and NICE CG116 - so you know what to expect and why.

  1. 01

    Assessing

    A careful, detailed history

    The single most important step - timing, quantity, food form, co-factors and reproducibility. History drives every test that follows.

  2. 02

    Assessing

    Distinguish allergy from intolerance

    Rule out non-immune mimics - FODMAP-sensitive IBS, lactase deficiency, gastro-oesophageal reflux and food aversion.

  3. 03

    Assessing

    Recognise the pattern

    Immediate (IgE), delayed GI or skin (non-IgE) or mixed - each needs a different diagnostic pathway.

  4. 04

    Confirming

    Skin prick testing

    A specialist allergy assessment - fast, sensitive and interpreted alongside the history, never in isolation.

  5. 05

    Confirming

    Specific IgE and components

    Blood tests including component-resolved diagnostics such as Ara h 2 (peanut), Cor a 14 (hazelnut) and Ana o 3 (cashew) improve accuracy.

  6. 06

    Confirming

    Tryptase and non-IgE work-up

    Peak tryptase at 1 to 3 hours plus baseline for suspected anaphylaxis. Elimination diets guide non-IgE patterns.

  7. 07

    Deciding

    Oral food challenge (OFC)

    The gold-standard test - performed only in specialist commissioned centres with full resuscitation cover.

Typical timeline: a first visit to a specialist plan in weeks, not months.

Symptoms

What food allergy actually looks like.

Immediate skin, airway and gut symptoms in IgE-mediated allergy, plus the delayed presentations of non-IgE and mixed patterns.

  • Urticaria and angioedema

    Hives and swelling of lips, tongue or face - a classic immediate IgE reaction within minutes to two hours.

  • Oral allergy symptoms

    Itching, tingling or mild swelling of the mouth and throat - often the first warning of an immediate reaction.

  • Respiratory symptoms

    Rhinorrhoea, cough, wheeze or stridor - upper and lower airway involvement raises the severity level.

  • Gastrointestinal symptoms

    Vomiting, cramping abdominal pain and diarrhoea - immediate in IgE, delayed in non-IgE (including FPIES and FPIAP).

  • Anaphylaxis

    Airway, breathing or circulation involvement - the life-threatening reaction that always needs intramuscular adrenaline.

  • Biphasic reactions

    A second wave of symptoms 1 to 72 hours after the first - seen in 5 to 15% and the reason for observation.

  • Eczema exacerbation

    Delayed worsening of atopic dermatitis - a common non-IgE and mixed-pattern presentation, especially in infants.

  • Red flag - collapse or stridor

    Any drop in blood pressure, stridor or reduced consciousness after food is anaphylaxis until proven otherwise.

Treatment

How food allergies are treated in the UK.

Strict avoidance and an emergency plan for everyone. Palforzia, omalizumab and dupilumab where they add real benefit under specialist care.

  • Strict allergen avoidance

    The cornerstone of care - label reading, Natasha's Law PPDS labelling, medical-alert bracelets and Anaphylaxis UK support.

  • Adrenaline auto-injector

    EpiPen, Emerade or Jext - 150 mcg under 30 kg, 300 mcg standard, 500 mcg adult. Two devices, IM into anterolateral thigh.

  • Emergency anaphylaxis plan

    Written action plan, in-date devices, oxygen, IV fluids and antihistamines or steroids as adjuncts - never instead of adrenaline.

  • Palforzia (peanut OIT)

    MHRA-approved oral immunotherapy for peanut allergy in specialist commissioned centres - see our clinic guide.

  • Omalizumab (Xolair)

    Anti-IgE biologic, MHRA and FDA-approved in 2024 to reduce food allergy reaction severity - specialist prescribing only.

  • Dupilumab for atopic overlap

    For co-existing moderate-to-severe atopic dermatitis or eosinophilic oesophagitis - specialist-led biologic therapy.

  • Early introduction (LEAP)

    Early peanut introduction from 4 to 6 months in high-risk infants reduces peanut allergy by around 80%.

  • MDT and patient support

    Allergy, dermatology, gastroenterology, dietetics and school or workplace planning with Anaphylaxis UK and Allergy UK.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your allergist knows your history and can tell you which parts apply to you. If in doubt, get seen.

  • BSACI. Standards of Care for food allergy (adults and children).

  • NICE CG116. Food allergy in under 19s - assessment and diagnosis.

  • WAO/WHO. Anaphylaxis guidance and international consensus on food allergy.

  • MHRA. Palforzia (2022) and omalizumab (2024) authorisations for food allergy.

Red flags

When food allergy needs urgent attention.

Most reactions are mild and self-limiting. These are the ones that need urgent action or specialist review.

  • Anaphylaxis

    Airway, breathing or circulation involvement after food - IM adrenaline, 999 and observation for 6 to 12 hours in hospital.

  • Biphasic reaction risk

    A second wave in 5 to 15% - the reason patients need to stay observed and carry two adrenaline devices.

  • Repeated accidental exposures

    Frequent inadvertent reactions signal a gap in avoidance strategy - review labels, kitchens and school or workplace plans.

  • Wheeze plus asthma

    Poorly controlled asthma is the biggest single risk factor for fatal food anaphylaxis - optimise inhalers urgently.

  • Faltering growth in infants

    Non-IgE cow's milk protein allergy, FPIES or FPIAP with weight loss needs urgent paediatric allergy or gastro review.

  • Suspected exercise or drug co-factors

    Food-dependent exercise-induced anaphylaxis, NSAIDs or alcohol can turn a tolerated food into a severe reaction.

  • Suspected eosinophilic oesophagitis

    Persistent dysphagia, food impaction or reflux unresponsive to PPIs - see our eosinophilic oesophagitis guide.

  • Suspected coeliac disease

    Wheat-triggered GI or systemic symptoms with weight loss or anaemia - see our coeliac disease guide before removing gluten.

  • Adrenaline device concerns

    Out-of-date, single-device supply or unclear training - specialist review before the next potential exposure.

Living with it

A serious condition, with a clear plan.

Four things that make the biggest difference day to day - reading labels, carrying two devices, planning for school or work, and asking about modern therapies.

A quiet reminder

Preparation, not fear, is the goal.

A written emergency plan and two in-date devices turn an emergency into a manageable event.

  1. 01 Avoid

    Read every label, every time

    Natasha's Law protects prepacked-for-direct-sale food. In restaurants, ask - and repeat the question if unsure.

  2. 02 Carry

    Two devices, always

    Two in-date adrenaline auto-injectors on you or your child, plus a written emergency plan and medical alert bracelet.

  3. 03 Plan

    School and workplace plans

    Named allergen action plan, training for staff and safe storage of devices - Access to Work can help adult employees.

  4. 04 Escalate

    Ask about newer options

    Palforzia for peanut and omalizumab for reducing reaction severity are now available in UK specialist centres.

Frequently asked

Everything we get asked about food allergies.

Quick answers on testing, anaphylaxis, Palforzia, omalizumab and prevention.

  • What is a food allergy?

    An immune-mediated adverse reaction to a food protein. It differs from food intolerance, which does not involve the immune system. Allergies are grouped into IgE-mediated (immediate), non-IgE-mediated (delayed) and mixed patterns, each with different symptoms and different diagnostic pathways.

  • How common are food allergies in the UK?

    True food allergy affects around 5% of adults and 8% of children. Self-reported allergy is much higher, at close to 20% of adults, which is why a careful history and specialist testing matter before restricting a diet or carrying an adrenaline device.

  • How is a food allergy diagnosed?

    A detailed clinical history is the foundation. Skin prick testing and specific IgE blood tests, including component-resolved diagnostics such as Ara h 2 for peanut, refine the picture. An oral food challenge in a specialist centre remains the gold-standard test where diagnosis is unclear.

  • What should I do during anaphylaxis?

    Use an adrenaline auto-injector immediately into the outer thigh, call 999, lie the person flat with legs raised (or sit up if breathing is difficult) and use a second device after 5 minutes if there is no improvement. Every anaphylaxis needs hospital observation for the biphasic reaction risk.

  • Is oral immunotherapy available on the NHS?

    Palforzia, a standardised peanut oral immunotherapy product, is MHRA-approved and commissioned in a small number of UK specialist paediatric allergy centres. Other food OIT programmes are emerging but remain limited to specialist commissioned services.

  • Can food allergies be prevented?

    For peanut, the LEAP trial showed that early introduction between 4 and 6 months in high-risk infants reduces peanut allergy by around 80%. Current UK guidance supports early introduction of allergenic foods in weaning, in line with normal developmental readiness.

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