paediatric allergy service news

Food allergies in children can be confusing because not all allergic reactions happen in the same way. Healthcare professionals generally classify food allergies into two main types: immediate (IgE-mediated) allergies and delayed (non-IgE-mediated) allergies. Understanding the differences can help parents recognise symptoms early and seek appropriate medical advice.

What is an Immediate (IgE-Mediated) Food Allergy?

An immediate food allergy occurs when the immune system produces antibodies called Immunoglobulin E (IgE) against a specific food protein. When the child eats that food, the immune system reacts quickly, releasing chemicals such as histamine that cause allergy symptoms.

When do symptoms occur?

Symptoms usually develop within a few minutes and up to two hours after eating the food.

Common symptoms

• Hives (urticaria)
• Itchy skin or rash
• Swelling of the lips, face, tongue, or eyes
• Itching in the mouth or throat
• Vomiting
• Wheezing, coughing, or breathing difficulties
• Dizziness or fainting
• Anaphylaxis, a severe and potentially life-threatening allergic reaction 

Common trigger foods

• Cow's milk
• Egg
• Peanut
• Tree nuts
• Fish
• Shellfish
• Wheat
• Soya
• Sesame

Diagnosis

Immediate allergies are usually diagnosed using a detailed allergy history along with skin prick tests and/or specific IgE blood tests, interpreted by an allergy specialist or healthcare professional.

What is a Delayed (Non-IgE-Mediated) Food Allergy?

A delayed food allergy does not involve IgE antibodies. Instead, other parts of the immune system are involved. Reactions occur more slowly, making it harder to identify the food responsible.

When do symptoms occur?

Symptoms may appear several hours or even a few days after eating the trigger food. In some children, symptoms can take up to 72 hours to become noticeable.

Common symptoms

• Persistent eczema
• Reflux or worsening reflux symptoms
• Diarrhoea or loose stools
• Constipation
• Blood or mucus in stools
• Abdominal pain
• Colic-like symptoms in babies
• Food refusal or feeding difficulties
• Poor growth or faltering growth in some children

 
Common trigger foods

• Cow's milk (the most common trigger)
• Egg
• Soya
• Wheat
• Other foods may occasionally be involved

Diagnosis

Skin prick tests and specific IgE blood tests are often negative. Diagnosis is usually based on a detailed clinical history and a supervised elimination and reintroduction of the suspected food.

Key Differences Between Immediate and Delayed Food Allergies 

Immediate (IgE-Mediated) Allergy

• Symptoms usually appear within minutes to two hours.
• May affect the skin, gut, and respiratory system.
• Can cause severe reactions, including anaphylaxis.
• Skin prick tests and specific IgE blood tests are often helpful.
• The link between the food and symptoms is usually easier to identify.

 

Delayed (Non-IgE-Mediated) Allergy

• Symptoms develop several hours to days after eating the food.
• Most commonly affects the skin and gastrointestinal system.
• Does not typically cause anaphylaxis.
• Skin prick tests and specific IgE blood tests are usually not helpful.
• Diagnosis often requires an elimination and reintroduction trial.

 

When Should Parents Seek Medical Advice?

Parents should seek advice from a healthcare professional if their child:

• Develops symptoms repeatedly after eating a particular food.
• Has persistent eczema that is difficult to control.
• Experiences ongoing gastrointestinal symptoms such as reflux, diarrhoea, constipation, or abdominal pain.
• Shows signs of poor growth or feeding difficulties.
• Experiences any immediate allergic reaction after eating a food.

Seek emergency medical help immediately if your child develops:

• Difficulty breathing
• Wheezing or severe coughing
• Significant swelling of the tongue or throat
• Collapse or loss of consciousness
• Symptoms of anaphylaxis

 

Important: Do not remove multiple foods from your child's diet without professional guidance, as unnecessary dietary restrictions can affect nutrition and growth.

References

1.    European Academy of Allergy and Clinical Immunology (EAACI). Guidelines on the Diagnosis of IgE-Mediated Food Allergy (2023). https://eaaci.org/guidelines-position-papers/eaaci-guidelines-on-the-diagnosis-of-ige-mediated-food-allergy/ 
2.    European Academy of Allergy and Clinical Immunology (EAACI). Guidelines on the Management of IgE-Mediated Food Allergy (2024). https://eaaci.org/guidelines-position-papers/eaaci-guidelines-on-the-management-of-ige-mediated-food-allergy/ 
3.    National Institute for Health and Care Excellence (NICE). Food Allergy in Under 19s: Assessment and Diagnosis (CG116). https://www.nice.org.uk/guidance/cg116 
4.    NHS. Food Allergies in Babies and Young Children. https://www.nhs.uk/baby/weaning-and-feeding/food-allergies-in-babies-and-young-children/
5.    Zhang S, Sicherer S, Berin MC, et al. Pathophysiology of Non-IgE-Mediated Food Allergy. ImmunoTargets and Therapy. 2021;10:431-446. 
6.    Venter C, Halken S, Toniolo A, et al. Diagnosing IgE-Mediated Food Allergy: How to Apply the Latest Guidelines in Clinical Practice. Journal of Allergy and Clinical Immunology: Global. 2025. 

Did you know? Introducing allergenic foods during infancy may help reduce the risk of developing food allergies. 

What the evidence shows

• Early introduction of common allergenic foods such as peanut, egg, dairy, wheat, soy, fish and sesame during the first year of life may help reduce allergy risk.
• The landmark LEAP study found that early and regular peanut introduction reduced the risk of peanut allergy by approximately 80% in high-risk infants.
• NIAID and AAP guidelines support the early introduction of peanut-containing foods, particularly for infants at increased risk. 

How Does It Work?

The immune system learns what is safe through exposure. When babies eat allergenic foods early and regularly, their immune system is more likely to develop tolerance to these foods instead of recognising them as harmful.

In simple terms:

• Early and regular exposure helps teach the immune system that a food is safe.
• Avoiding allergenic foods for long periods may increase the likelihood that the immune system will react to them later.

Some evidence also suggests that some babies, particularly those with eczema, may become sensitised to foods through their skin before they eat them. Introducing allergenic foods by mouth early may help prevent this process and promote tolerance.

 

Practical Tips for Parents 

• Introduce one new allergenic food at a time.
• Offer foods in age-appropriate forms and avoid choking hazards such as whole nuts.
• Continue offering tolerated foods regularly.
• Seek medical advice before introduction if your baby has severe eczema or a known food allergy. 

Key Message 

Early, safe, and regular introduction of allergenic foods is now considered an important strategy in helping to prevent food allergies. 

References 

1. NIAID Addendum Guidelines for the Prevention of Peanut Allergy in the United States (2017). 

2. American Academy of Pediatrics. Updates in Food Allergy Prevention in Children (2023). 

3. HealthyChildren.org (AAP). Early Introduction of Peanut-based Foods to Prevent Allergies. 

4. Food Allergy Research & Education (FARE). Early Introduction and Food Allergy Prevention. 

For many families, living with food allergies can be overwhelming. I have seen first-hand how the increasing number of children diagnosed with allergies has led to significant stress, anxiety, and lifestyle changes. Simple activities such as eating out, attending birthday parties, or travelling abroad can become major sources of worry for parents and children alike.

I am proud to say that our paediatric allergy service has now successfully started providing Oral Immunotherapy (OIT), also known as oral food desensitisation. This treatment is already making a meaningful difference to the lives of many of our patients and their families by helping to build confidence and improve quality of life.

OIT involves offering patients very small amounts of the food they are allergic to every day, gradually increasing the dose over time to help build tolerance. While it is not a cure for food allergies, it can significantly reduce the risk of severe reactions from accidental exposure and provide families with greater peace of mind.

Dr Rajiv Sood runs the immunotherapy clinic within the Starlight Outpatients Department alongside our specialist allergy nurses and our specialist allergy dietician, whose expertise and dedication are central to the success of the service. We currently offer desensitisation for peanut, egg, cashew and milk. We are also hoping to provide a variety of other food OIT in the future and continue to gain knowledge on how to do this.

This type of service is not always readily available across many NHS trusts due to the time, resources, and specialist knowledge required to deliver it safely. OIT requires careful monitoring, regular follow-up, and highly trained staff to support patients throughout the process.

Seeing the positive impact this service has had on families has been incredibly rewarding. Parents have shared how their children now feel more confident attending social events, eating in restaurants, and travelling with less fear and anxiety. For many, it has given them a sense of normality that they had been missing for years.

As our service continues to grow, we remain committed to providing safe, compassionate, and specialist care for children with allergies and supporting families every step of the way.

 

From left to right: Dr Rajiv Sood Consultant Paediatrician, Yvette Oppong-Kwarteng Paediatric Allergy CNS, Maria D’Cruz Paediatric Nurse with an interest in allergy, Juli Khatun Paediatric Allergy CNS, Yvonne Polydorou Highly specialist allergy dietician.