Identifying high-risk infants and reducing food allergy risk in primary care  

Primary care professionals play a vital role in the early identification and management of infants at high risk of allergy. Allergy UK’s “I Wish I Knew” campaign highlights the importance of recognising allergy risk early and guiding families on safe allergen introduction to help reduce the risk of food allergy.
Food allergy is a common concern in early childhood and can cause a great deal of anxiety for parents, particularly with regard to weaning. The causes of food allergy are multifactorial and include genetics, environmental influences, immune dysregulation, reduced microbial diversity and impaired skin barrier function.   

Eczema increases risk of food allergy as allergic sensitisation is more likely to occur via the transcutaneous route. Eczema should be identified and managed as soon as possible with adequate support from healthcare professionals to reduce risk. Effective eczema management should not only include the usual consistent treatment with emollients or topical therapies, but also clear instructions on avoiding skincare products containing food ingredients and careful hygiene practices when applying creams or handling the infant to minimise the risk of allergen exposure. Using creams and lotions with pumps or a dedicated spatula or spoon for tubs can help minimise contamination and exposure to allergens. GPs, primary care nurses and health visitors can support with the education and implementation of this advice.  

Infants at higher risk of developing food allergies include those with moderate to severe eczema, particularly with onset in the first three months of life, plus infants who already have an allergy, such as cow’s milk allergy. These infants are likely to benefit from early introduction of egg and peanut once they are developmentally ready for solid foods as early and regular oral intake of the foods can promote oral tolerance. Introduction should not be attempted before age 4 months, should start after non-allergenic pureed vegetables have been introduced and start with small amounts, gradually increased if tolerated. Parents/caregivers should be encouraged to introduce new allergenic foods one at a time, monitor for reactions and offer foods earlier in the day when supervision is easier. Introduction of other common allergens such as wheat, fish, sesame, and tree nuts should not be delayed if they are eaten by the family.  

Parents should be actively discouraged from offering allergenic foods merely to test for allergy if there is no intention to keep the food regularly in the diet as this could increase risk of allergic sensitisation. Ongoing exposure to tolerated allergenic foods helps promote oral tolerance 1. 

Emerging evidence suggests exposure to ultra-processed foods (UPFs) and common ingredients in UPFs, including fructose and sugar, are associated with increased occurrence of allergic diseases, and that higher intake of commercial baby foods is linked to food allergy. Further research is needed to confirm causality. Infants in the UK can be exposed to high levels of free sugars from commercial baby foods. Families should be encouraged to provide home-cooked food whenever possible.  

The quality of diet of pregnant women may also affect risk of allergic diseases 3. Avoidance of particular foods in the maternal diet during pregnancy and while breastfeeding has not been shown to prevent food allergies in infants. Pregnant and breastfeeding women should be advised to eat a varied, healthy and balanced diet. Research on the use of nutritional supplements during pregnancy for allergy prevention remains inconclusive 4. Standard health recommendations for folic acid and vitamin D supplementation during pregnancy remain unchanged.   

Most allergic reactions in infants are mild to moderate, but severe reactions do occur. Non-allergic reactions, such as redness or rash around the mouth or mild gastrointestinal symptoms, are common and often triggered by fruit, vegetables, or other irritants rather than typical allergens. Parents and caregivers should be reassured when a reaction is likely non-allergic. Non-IgE-mediated allergic reactions are often delayed, appearing hours to days after ingestion, and typically involve the gastrointestinal tract or skin. The symptoms frequently overlap with common infant complaints such as reflux, colic, loose stools or constipation, making it important to rule out non-allergic causes and take a thorough allergy-focused history to assess the likelihood of food allergy. Diagnosis of non-IgE-mediated allergies is based on clinical history and food elimination followed by food re-introduction to confirm the diagnosis.  

Food Protein-Induced Enterocolitis Syndrome (FPIES) is a rare but severe form of non-IgE-mediated allergy in which ingestion of a trigger food can result in profuse vomiting and/or diarrhoea, typically 1- 4 hours later. Symptoms suggestive of FPIES should be taken seriously and prompt referral to specialist allergy services. Severe reactions may lead to dehydration and hypovolaemic shock and require emergency medical support. Trigger food must be strictly avoided and food introductions should be supervised by specialist services.   

Children presenting with persistent feeding difficulties, food refusal, a preference for soft or wet foods, difficulty swallowing, recurrent vomiting, abdominal pain, heartburn or chest pain, poor weight gain, recurrent food impaction, or symptoms unresponsive to standard reflux treatment should be considered for assessment of eosinophilic oesophagitis (EoE) and referred to paediatric gastroenterology if clinically indicated. EoE is the most common eosinophilic gastrointestinal disorder (EGID) and may be triggered by food allergy. Other, less common EGIDs include eosinophilic gastritis, gastroenteritis, and colitis. Early recognition and specialist referral are important to prevent complications and to guide appropriate dietary and medical management.  

With the exception of FPIES and EoE, management of non-IgE-mediated food allergies focuses on avoidance of the trigger food only in the form that causes reactions, combined with re-introduction after a period of avoidance, while monitoring for symptoms. Antihistamines are typically not required.  

IgE-mediated reactions are typically immediate, occurring within minutes but sometimes up to two hours after exposure. They may include urticaria, erythematous rash, vomiting, and less commonly respiratory compromise or hypotension. Severe reactions (anaphylaxis) affecting the airways, breathing or consciousness/circulation (ABC) require urgent emergency care. Immediate administration of adrenaline, if available, is essential. The child should be placed supine with legs raised while remaining still until help arrives, unless breathing is difficult, in which case they should be allowed to sit upright.   

IgE-mediated allergies require strict avoidance of the trigger food, except for forms that are known to be tolerated, which should be continued. Diagnosis should be based on a thorough allergy-focused clinical history, with skin prick or blood tests used as a supplement if needed. Positive test results alone do not confirm allergy and must always be interpreted in the context of the clinical history. Referral to specialist allergy services is recommended for most cases of IgE-mediated food allergy, except for children with mild to moderate egg allergy who have no history of anaphylaxis or ongoing respiratory concerns, no severe eczema or multiple food allergies. In such children, home introduction of egg is recommended from around 12 months of age, following a graded ladder approach, if tolerated, and may help support the development of tolerance 5. Children at risk of severe reactions should receive specialist care and may require hospital-supervised food introductions.  

Diagnosis of IgE-mediated food allergy should prompt the prescription of appropriate rescue medications, including antihistamines and adrenaline auto-injectors, if indicated and the provision of an allergy action plan. This plan guides parents and caregivers on how to recognise allergic symptoms and respond appropriately, ensuring safety while supporting the gradual introduction of tolerated forms of egg where clinically appropriate.  

Primary care professionals should identify high-risk infants early, explain the mechanism of transcutaneous sensitisation, and advise on early introduction of egg and peanut while avoiding unnecessary delays for other allergens. Families should be supported to recognise mild irritant reactions and differentiate them from true allergic reactions. They should be empowered to manage mild reactions at home and know when to escalate care. Structured reintroduction protocols such as the milk ladder or BSACI egg ladder should be used under professional guidance. Complex cases should be referred to specialist services.  

Key points for reducing risk of food allergy in infants  

• Manage eczema proactively 
  Early and consistent eczema treatment helps maintain skin barrier function and may reduce the risk of transcutaneous sensitisation 6  

• As part of eczema management, advise on avoidance of food-based ingredients in skincare products and promote scrupulous hand hygiene   

Clean hands and avoidance of food ingredients are crucial for limiting skin exposure to allergens. Dispensers with pumps or a dedicated spatula/spoon for tubs are helpful.  

• Identify high-risk infants early 
  Infants with early-onset or moderate-severe eczema, or existing food allergy, may benefit from proactive and tailored advice. Referral to specialist services may be needed, but primary care healthcare professionals can also support effective management.  

• For high risk infants, recommend early introduction of egg and peanut   

The infant should be developmentally ready and swallowing pureed vegetables first to ensure that egg/peanut is swallowed and not exposed to skin only. See BSACI guidance for health professionals and parents.

• Advise not delaying introduction of other allergens 
  Foods like milk, wheat, fish and seafood, sesame and tree nuts should be introduced within the first year of life, if part of the family diet.   

• Advise regular ingestion of tolerated allergens 
  Once introduced and tolerated, allergenic foods should be offered regularly to help maintain oral tolerance. Fruit and vegetables are not typical allergens and can be eaten seasonally. There is no confirmed risk of delaying the introduction of fruits or vegetables linked to non-allergic irritant reactions, such as those sometimes seen with tomato, strawberries, or citrus  

• Discourage “testing” of foods without intention to continue 
  Parents/caregivers should be discouraged from introducing allergenic foods to test for an allergic reaction without intention of keeping the food in the diet. This may increase sensitisation risk.   

• Encourage home-prepared foods 
  Advise that ultra-processed foods are associated with adverse health outcomes, including higher risk of allergic diseases. Commercially prepared baby foods are often high in sugar and low in important nutrients such as iron. Home-cooked foods support health and nutrition.   

• Support and educate parents 
  Provide practical advice on allergen introduction, signs of allergic reactions and non-allergic irritational reactions and when to seek help. Reassure and empower families.   

References:  

1. Nuyttens L, De Vlieger L, Diels M, Schrijvers R, Bullens DMA. The clinical and immunological basis of early food introduction in food allergy prevention. Front Allergy. 2023;4:1111687. Published 2023 Jan 23. doi:10.3389/falgy.2023.1111687  
2. Berni Canani R, Carucci L, Coppola S, et al. Ultra-processed foods, allergy outcomes and underlying mechanisms in children: An EAACI task force report. Pediatr Allergy Immunol. 2024;35(9):e14231. doi:10.1111/pai.14231  
3. Venter C, Pickett-Nairne K, Leung D, et al. Maternal allergy-preventive diet index, offspring infant diet diversity, and childhood allergic diseases. Allergy. 2024;79(12):3475-3488. doi:10.1111/all.16292  
4. Halken S, Muraro A, de Silva D, et al. EAACI guideline: Preventing the development of food allergy in infants and young children (2020 update). Pediatr Allergy Immunol. 2021;32(5):843-858. doi:10.1111/pai.13496  
5. Leech SC, Ewan PW, Skypala IJ, et al. BSACI 2021 guideline for the management of egg allergy. Clin Exp Allergy. 2021;51(10):1262-1278. doi:10.1111/cea.14009  
6. Yamamoto-Hanada K, Kobayashi T, Mikami M, et al. Enhanced early skin treatment for atopic dermatitis in infants reduces food allergy. J Allergy Clin Immunol. 2023;152(1):126-135. doi:10.1016/j.jaci.2023.03.008