Owing to the fact allergies are on the rise in young children, it is no surprise parents are concerned about introducing foods commonly allergenic when weaning. Additionally, since the advice on this has changed over recent years it can also be a little confusing for parents too. Here we explain what a food allergy is, how it differs from a food intolerance, and what the advice is around introducing these when weaning.
Food allergies vs. intolerances

Food allergies and intolerances fall under the umbrella of ‘food hypersensitivities’, which describes when someone has an adverse reaction to food. If this reaction is a result of the immune system response it is a food allergy, otherwise it is a food intolerance.
Food allergies have one further layer, and that is whether they are IgE or Non-IgE mediated; which essentially describes the component within the immune system that is leading the response. Immunoglobin E (IgE) is an antibody produced by the immune system. In an IgE-mediated allergy, the antibody responds to a food protein and triggers a reaction by the immune system. This will typically be rapid, within roughly two hours after contact with the food, and symptoms vary from mild to severe and, in some instances, life-threatening (e.g. anaphylaxis). Non-IgE allergies are when this antibody is not involved and instead the onset of symptoms can be slower, occurring up to a few days later.
Allergic symptoms
Symptoms of allergic reaction can include; swelling or itchiness around the eyes, mouth or throat, difficulty breathing, skin irritations (e.g. eczema and hives) and digestive complaints such as constipation or diarrhoea. However, this is not an exhaustive list and it is worthwhile familiarising yourself with the full list of possible symptoms* before commencing introduction.
*For full list of the symptoms to look out for and further advice on allergen introduction head to Allergy UK.
The allergens
The most common food allergens in children are cow’s milk, eggs, shellfish, fish, soy, sesame, peanuts*, tree nuts* and wheat. In the UK, legislation requires that all of these plus mustard, celery, sulphites, molluscs and lupin are listed on pre-packaged food labels. UK guidelines advise introducing all these common allergens from around 6 months when weaning. There is no evidence to suggest delaying introduction reduces the risk of allergic reactions. In fact, there’s some evidence to suggest delaying introduction of peanuts and hen’s eggs until after 12 months may increase the risk of allergic reaction. Delayed introduction of gluten is not shown to reduce the risk of coeliac disease.
*Ensure peanuts & tree nuts are finely chopped or ground when served to those under 5 years old.
How to introduce allergens

- When introducing allergens, first make sure your little one is well and doesn’t have a cough, common cold or stomach upset as the symptoms of these can be confused as a reaction to the food.
- When starting, introduce each allergen one at a time, leaving roughly three days in between each.
- Start with small amounts, working up to a full portion over 3-4 days.
- Once your little one is tolerating a new food continue to provide it in their diet whilst continuing to introduce new foods.
- If you suspect a reaction to a food, discontinue the introduction and seek medical advice.
You may be particularly cautious of introducing allergens if your little one has a known food allergy, eczema or asthma, or there is family history of such. Whilst these factors do not necessarily mean your little one will have an allergic reaction, it is advised that you seek medical advice from your health care professional before proceeding.
It’s worth noting that certain acidic foods, such as strawberries, tomatoes and citrus fruits, can cause redness (particularly around the mouth) upon consumption. This is likely a contact reaction, rather than an allergy. A baby’s skin is very sensitive, and may similarly become irritated if you rub an allergen on it. For this reason, rubbing allergens on the skin is not a recognised way of introducing an allergen and determining if your child may be allergic.