Safely Introducing Allergens to Your Baby
Everything you need to know about safely introducing common food allergens during weaning
As a parent, introducing solid foods is an exciting milestone, but it can also bring feelings of anxiety—especially when it comes to food allergens. For decades, parents were advised to delay giving babies common allergenic foods like peanuts and eggs. However, groundbreaking research has completely shifted this guidance. Today, paediatricians, the NHS, and the British Society for Allergy and Clinical Immunology (BSACI) agree: introducing allergens early and serving them often is one of the most effective ways to prevent food allergies from developing [1] [2].
This guide, written with the expertise of paediatric nutrition principles, will walk you through the why, when, and how of safely introducing food allergens to your baby in the UK.
Why Early Introduction Matters
The shift in medical advice began largely with the 2015 Learning Early About Peanut Allergy (LEAP) study. This landmark trial demonstrated that introducing peanut products to high-risk infants between 4 and 11 months of age reduced their risk of developing a peanut allergy by up to 81% by age 5 [1] [3].
Following this, the NHS and BSACI updated their guidelines. They now strongly endorse the early introduction of peanut-containing foods, and similar principles are being applied to other common allergens like egg [4]. The core message is clear: early and consistent exposure helps train your baby's immune system to tolerate these foods.
Assessing Your Baby's Risk Level
Before starting, it is important to understand your baby's individual risk for food allergies. The primary risk factors are severe eczema and a pre-existing food allergy [5].
| Risk Level | Characteristics | Recommendation |
|---|---|---|
| High Risk | Severe eczema, an existing egg allergy, or both. | Consult your GP or health visitor before introducing allergens. They may recommend allergy testing or supervised introduction. Introduction often begins early, from 4 months of age [2]. |
| Moderate Risk | Mild to moderate eczema. | Introduce common allergens at home starting around 6 months of age (but not before 4 months), in accordance with your family's cultural practices [5]. |
| Low Risk | No eczema and no known food allergies. | Introduce allergens at home alongside other solid foods, typically around 6 months of age [4]. |
"Evidence has shown that delaying the introduction of peanut and hen's eggs beyond 6 to 12 months may increase the risk of developing an allergy to these foods." — NHS [4]
Note: A family history of food allergies or having a sensitive stomach does not automatically place a baby in the high-risk category, but always discuss any concerns with your health visitor or GP [6].
The 14 Major Allergens in the UK
While a baby can be allergic to any food, UK food law identifies 14 major allergens that must be highlighted on packaging. When introducing these, ensure they are prepared in a baby-safe texture to prevent choking [4] [6].
| Allergen | Baby-Safe Preparation Ideas | Safety Tip |
|---|---|---|
| Peanuts | Smooth peanut butter thinned with water or breastmilk/formula. | Never serve whole peanuts or thick globs of peanut butter, which are choking hazards. |
| Eggs | Well-cooked scrambled eggs or hard-boiled eggs mashed into tiny pieces. | Eggs with the Red Lion stamp can be eaten lightly cooked, but fully cooked is best to start. |
| Cows' Milk | Plain, full-fat yoghurt or soft pasteurised cheeses like ricotta. | Do not give cows' milk as a main drink before 12 months, but dairy foods are fine. |
| Tree Nuts | Smooth almond or cashew butter thinned with water. | Introduce one type of tree nut at a time. |
| Soya | Mashed soft tofu or plain soya yoghurt. | - |
| Cereals containing Gluten | Wheat-based infant cereal cooked with water or breastmilk. | Includes wheat, rye, barley, and oats. |
| Fish | Flaked, fully cooked low-mercury fish (e.g., salmon, cod). | Double-check for small bones. |
| Crustaceans / Molluscs | Finely chopped, fully cooked prawns or crab. | Ensure all shells are removed. |
| Sesame | Tahini thinned with water or mixed into a puree. | - |
Other major allergens include celery, mustard, lupin, and sulphur dioxide (often found in dried fruits).
Step-by-Step Guide: How to Introduce Allergens
Introducing allergens does not have to be intimidating. Follow these steps to ensure a safe and calm experience for both you and your baby [4] [6].
1. Choose the Right Time and Place
Always introduce a new allergen at home, never at a restaurant or nursery. Choose a time early in the day, such as breakfast or after a morning nap. This ensures that you can monitor your baby for at least two hours afterward, and it is easier to contact your GP if a reaction occurs [6].
2. Introduce One Allergen at a Time
Only introduce one new allergenic food at a time. Wait 2 to 3 days before introducing another new allergen. This way, if your baby has a reaction, you will know exactly which food caused it [4].
3. Start Small
Begin with a very small amount—about 1/4 of a teaspoon of the allergenic food. Offer it on the tip of a spoon. If your baby refuses, do not force it. You can try again later [6].
4. Wait and Observe
After the first small bite, wait 10 to 15 minutes. Watch closely for any signs of an allergic reaction. If there are no symptoms, you can offer the rest of the baby-sized serving [6].
5. Keep it in the Diet
This is a crucial step: once an allergen is introduced and tolerated, you must keep it in your baby's regular diet. Aim to serve it at least twice a week. Consistent exposure is what builds and maintains tolerance [2] [4].
Recognising an Allergic Reaction
It is vital to know the difference between a normal physical response (like a mild contact rash from acidic foods like tomatoes) and a true allergic reaction. Reactions usually occur within minutes to two hours after eating [4].
Mild to Moderate Symptoms
If you notice these symptoms, stop feeding the allergen and contact your GP or call NHS 111 [4] [7]:
- A red, itchy rash or hives.
- Swollen lips or face.
- Red, itchy, watery eyes.
- Sneezing or a runny/blocked nose.
- Tummy pain, vomiting, or diarrhoea.
Severe Symptoms (Anaphylaxis)
Anaphylaxis is a severe, potentially life-threatening allergic reaction. If you observe any of the following, call 999 immediately and ask for an ambulance [4] [7]:
- Breathing problems, wheezing, or a persistent cough.
- Swelling of the throat or tongue.
- Pale, floppy, or unresponsive behaviour.
- Sudden lethargy or tiredness.
Final Thoughts
Introducing allergens is a vital step in your baby's weaning journey. By starting early, starting small, and serving these foods regularly, you are actively helping to protect your child from developing food allergies. Remember, you are not alone in this—consult your health visitor or GP to create a plan that feels safe and right for your family.
References
[1] Du Toit, G., et al. (2015). Randomized Trial of Peanut Consumption in Infants at Risk for Peanut Allergy. New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMoa1414850
[2] BSACI. (n.d.). Early introduction of food allergens. https://www.bsaci.org/resources/allergy-management/food-allergy/allergy-prevention/early-introduction-of-food-allergens/
[3] National Institutes of Health. (2024). Introducing peanut in infancy prevents peanut allergy into adolescence. https://www.nih.gov/news-events/news-releases/introducing-peanut-infancy-prevents-peanut-allergy-into-adolescence
[4] NHS. (2024). Food allergies in babies and young children. https://www.nhs.uk/baby/weaning-and-feeding/food-allergies-in-babies-and-young-children/
[5] BSACI. (2020). Preventing food allergy in your baby: A summary for parents. https://www.bsaci.org/wp-content/uploads/2020/02/pdf_Infant-feeding-and-allergy-prevention-PARENT-SUMMARY-FINAL.pdf
[6] Solid Starts. (2023). Introducing Food Allergens to Baby. https://solidstarts.com/allergies-babies/
[7] Solid Starts. (2023). Symptoms of Allergic Reactions in Babies. https://solidstarts.com/symptoms-of-allergic-reactions/