Experts explain how parents can recognise food allergies, confirm diagnosis and respond to potentially life-threatening reactions. Food allergies can be frightening for parents, particularly when a child's reaction happens suddenly after eating something they have previously tolerated.

An allergic reaction can range from mild itching or hives to anaphylaxis, a potentially life-threatening reaction that can affect breathing and circulation. Knowing the symptoms and having an emergency plan can help families respond quickly.

The NHS says food allergy symptoms can affect different parts of the body and may include a raised, itchy rash, swelling, coughing, wheezing, vomiting, tummy pain and diarrhoea.

What Are the Symptoms of a Food Allergy?

Food allergy symptoms can develop shortly after eating an offending food, although some reactions may take longer to appear.

Common signs include:

  • Skin reactions. Hives, itching, redness or swelling can be early signs of an allergic reaction.
  • Swelling. The lips, face, eyes, mouth or throat may become swollen.
  • Breathing problems. Wheezing, coughing, noisy breathing or breathlessness can indicate a more serious reaction.
  • Digestive symptoms. Vomiting, diarrhoea or abdominal pain can occur.

A child may experience symptoms affecting several parts of the body at the same time. Food allergy should also be distinguished from food intolerance, which generally does not involve the immune system in the same way.

When is a Food Allergy an Emergency?

Anaphylaxis can develop rapidly and requires immediate treatment.

Parents should call 999 if a child develops sudden swelling of the mouth, lips, tongue or throat, has difficulty breathing or swallowing, becomes faint or confused, or becomes floppy or unresponsive.

If a child has been prescribed an adrenaline auto-injector, such as an EpiPen, it should be used immediately during a suspected severe allergic reaction. Parents should then call 999 and tell the operator that the child is experiencing anaphylaxis.

Do not wait to see whether severe symptoms improve on their own.

What Should Parents Do After an Allergic Reaction?

Even if symptoms settle, a child who has experienced a suspected significant allergic reaction should be assessed by a healthcare professional.

Parents should make a note of:

  • What the child ate. Include ingredients and approximate quantities where known.
  • When symptoms began. The timing can help doctors establish whether an immediate food allergy is likely.
  • What symptoms occurred. Record skin, breathing, digestive or cardiovascular symptoms.
  • What treatment was given. Include adrenaline, antihistamines or other medication.

This information can help an allergy specialist determine what happened and whether further testing is appropriate.

How Are Food Allergies Diagnosed?

There is no single test that can diagnose every food allergy.

In the UK, NICE recommends taking an allergy-focused clinical history before conducting tests. When an IgE-mediated food allergy is suspected, healthcare professionals may use a skin-prick test or a blood test measuring specific IgE antibodies.

A positive allergy test does not necessarily mean that eating the food will cause a clinical reaction. Testing needs to be interpreted alongside the child's symptoms and medical history.

In some cases, an oral food challenge may be used to clarify whether a child is genuinely allergic. This involves gradually giving measured amounts of the suspected food under specialist medical supervision because a reaction can occur.

Parents should not attempt an oral food challenge at home.

Should Parents Remove Foods From a Child's Diet?

Parents should avoid removing multiple foods from a child's diet without professional guidance.

Unnecessary food avoidance can make meals more complicated and may affect a child's nutrition, particularly when several major food groups are excluded. Diagnostic testing can also prevent families from unnecessarily restricting foods that a child can safely eat.

Children with a confirmed allergy should, however, strictly avoid the relevant allergen according to advice from their healthcare team.

Schools, nurseries, childminders and other carers should also be informed and given clear instructions about avoiding the allergen and responding to an emergency.

Could a New Treatment Reduce the Risk of Accidental Exposure?

For some children with confirmed food allergies, treatment options are expanding.

Dr Joyce Yu, a paediatric allergist at Columbia University, has discussed omalizumab (Xolair), a monoclonal antibody that targets immunoglobulin E (IgE), the antibody involved in allergic reactions. She describes the treatment as having the potential to significantly affect paediatric allergy management.

In the US, the Food and Drug Administration (FDA) approved Xolair in 2024 for certain adults and children aged one year and older with IgE-mediated food allergies, to reduce allergic reactions, including anaphylaxis, following accidental exposure to one or more foods.

However, Xolair does not cure food allergy, does not mean children can deliberately eat their allergens and is not an emergency treatment for anaphylaxis. Patients must continue avoiding their known allergens.

The FDA approval was supported by a trial involving children and adults allergic to peanuts and at least two other foods. Among participants receiving Xolair, 68 per cent were able to tolerate a specified single dose of peanut protein without moderate-to-severe symptoms, compared with 6 per cent receiving placebo.

Availability and licensing can differ between countries, so UK families should discuss eligibility and current treatment options with an NHS allergy specialist.

What Should Parents Keep in an Allergy Action Plan?

A written allergy plan can make an emergency easier to manage, particularly when a child spends time away from home.

It should clearly state the child's confirmed allergens, symptoms of a serious reaction, prescribed medication and instructions for using an adrenaline auto-injector.

Parents should ensure that two adrenaline auto-injectors are available when prescribed, with appropriate devices provided to school or childcare settings according to the child's individual plan.

Children who are old enough should gradually learn about their allergy and how to recognise symptoms, while adults remain responsible for ensuring appropriate precautions are in place.

Can Children Outgrow Food Allergies?

Some childhood food allergies can resolve as children get older, while others are more likely to persist.

Whether an allergy has been outgrown depends on the food involved, the child's medical history and their allergy test results. Parents should not test this by giving the food at home.

An allergist may determine whether a medically supervised oral food challenge is appropriate. Such challenges are conducted in settings equipped to treat severe allergic reactions.

Know Your Kids' Allergens

Food allergies can cause anything from hives and vomiting to potentially fatal anaphylaxis. Parents should learn their child's symptoms, avoid confirmed allergens and know exactly how to use prescribed emergency medication.

Testing should be based on a detailed medical history and interpreted by appropriately trained healthcare professionals rather than relying on an allergy test alone.

Newer treatments such as omalizumab may help reduce the risk associated with accidental exposure for selected patients, but they do not replace allergen avoidance or emergency adrenaline.

If a child develops breathing difficulties, throat or tongue swelling, faintness, severe dizziness or becomes floppy or unresponsive after eating, use their adrenaline auto-injector if prescribed and call 999 immediately.

Frequently Asked Questions

  • What are the symptoms of a food allergy?
    Symptoms can include hives, swelling, breathing difficulties, and digestive issues.
  • When is a food allergy considered an emergency?
    An emergency occurs when symptoms like sudden swelling, difficulty breathing, or unresponsiveness develop, requiring immediate medical attention.
  • How are food allergies diagnosed?
    Diagnosis involves taking an allergy-focused clinical history and may include skin-prick tests or blood tests for specific IgE antibodies.
  • Should parents remove foods from a child's diet?
    Parents should avoid removing multiple foods without professional guidance to prevent nutritional deficiencies.
  • Can children outgrow food allergies?
    Some children may outgrow food allergies, but this depends on the specific allergen and the child's medical history.
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