Every parent gets nervous about their baby developing a food allergy, and that’s totally understandable. It’s recommended that babies are introduced to allergens during weaning, so they’ll be less likely to develop an allergy. Vhi consultant paediatrician, Dr Aisling Stafford, explains why this is the case, the types of food allergies, and tips for introducing allergens to your baby’s diet.

Weaning is when we start introducing babies to solid food. It should start when your baby is about six months, and never younger than 17 weeks. This is the case whether you’ve been breastfeeding or formula feeding your baby. It’s a fun, messy and exciting time for both parents and babies!

Common food allergies in babies

It’s important to say that babies aren’t born with food allergies. They develop after birth and are more likely to occur if allergens (foods that cause allergic reactions) are delayed when a baby is being weaned. A food allergy is your body's immune system reacting incorrectly to specific proteins that are found in foods. Your immune system sees the food as a threat and responds with the symptoms associated with an allergic reaction. The most common food allergies we see in babies are egg, milk, soya, wheat, and nuts. Fish and sesame allergies are seen a bit more in older babies and children.

The two types of food allergies

There are two types of food allergies, and each one causes different symptoms. The two types are immediate food allergies and delayed food allergies:

Immediate food allergy: this is an allergy that’s driven by an antibody (an antibody is a protein that your immune system produces to get rid of unwanted things from your body like bacteria and viruses). With an immediate food allergy, you’ll usually see symptoms within a few minutes up to two hours of your baby eating the triggering food. Any time your baby has the food they are allergic to, reproducible symptoms will occur. Symptoms can include vomiting, diarrhoea, rash, swelling of the skin and lips and sometimes there can be difficulty breathing. These allergies are treated with antihistamines and sometimes adrenaline will be needed (given as adrenaline pens). If you think your baby is having an immediate food allergy, stop giving them the food and reach out to your healthcare provider for guidance. Generally, your baby will be referred for an evaluation and this might include skin prick or blood testing. Severe reactions are very rare, but if your baby is reacting severely or struggling to breathe, call emergency services straight away for assistance. Severe reactions can cause symptoms such as swelling of the throat and tongue, noisy breathing, difficulty breathing or swallowing, skin that feels cold or is blue or pale, or the baby becoming floppy and sleepy.

Delayed food allergy: this type of allergy is not driven by an antibody, and it takes between two and 24 hours for symptoms to start. It can affect the skin or the gut. The symptoms can include tummy pain, vomiting, diarrhoea, blood in the stools, and irritability. This type of allergy is common in babies that are allergic to cow’s milk. There are no blood tests available to diagnose a delayed food allergy; instead, your healthcare provider will evaluate your baby and suggest an elimination diet (such as eliminating dairy if they feel dairy could be the culprit), to see if the symptoms stop. It’s recommended you try this elimination diet for four to six weeks before re-introducing the food to see if the symptoms come back again. The symptoms of a delayed food allergy are very similar to those of lots of other conditions, so be sure to chat to your healthcare provider who can work through your baby’s symptoms and figure out if an allergy is the root cause.

Note: The Vhi paediatric clinic treats delayed allergic reactions only. Please contact your GP for mild immediate allergic reactions, and emergency services if your baby is having a severe immediate allergic reaction.

The importance of introducing allergens to your baby’s diet

It’s safe and recommended to introduce allergens to your baby’s diet pretty much as soon they have started weaning. When a baby eats a food and it passes through their digestive system, they become tolerant of the food. When their body is tolerant of a food, it won’t produce antibodies to fight against it (like it would a bacteria or virus), causing an allergic reaction. It’s recommended you don’t delay introducing a specific food (such as nuts, dairy, wheat, or eggs) into your baby’s diet. This is especially important if your baby has eczema as they can develop a sensitivity to it during this time and become allergic.

Tips and tricks for introducing allergens to your baby’s diet

It’s best for your baby to introduce all the allergens as you’re weaning them. There’s no need to hold off doing so unless your healthcare provider recommends it. Here are some tips and guidelines:

• Introduce the foods one-by-one. Don’t introduce more than one allergen at a time. This way, you’ll know for sure what causes an allergic reaction if your baby has one.
• You could start with dairy, then hard boiled eggs (mashed up) and then smooth nut butters. An easy way to introduce dairy is to add milk or yoghurt to the purées you make. Another is if you choose to do complimentary feeding with your baby; complimentary feeding is when you introduce your baby to solid foods while still formula feeding for some meals.
• For nut butters, I recommend adding some hot water to loosen it, then add it to their porridge or just spoon-feed them a couple of portions.
• From here, introduce soya, wheat and fish one-by-one, in any order you prefer.
• When introducing dairy, egg, nuts or fish to your baby’s diet for the first time, start with at least a teaspoon and build this up as your baby’s appetite grows with their age.
• When giving your baby any of the allergens for the first couple of times, give them the food directly off a spoon. Don’t give them the spoon or the food to feed themselves; this is to make sure that the least amount of food as possible gets onto their skin. This could potentially cause their skin to become sensitised to the food. Applying a barrier cream or ointment around their mouth before giving them food is a useful tip.
• When introducing nuts, never give whole or chopped nuts, but crush them up instead. You can then sprinkle these crushed pieces into a powder and sprinkle it onto your baby’s food. Buy specific types of nuts individually and try them one-by-one, rather than buying mixed bags. Once your baby has tried each type of nut and had no allergic reaction, you can crush mixed nuts and continue to add them to their food.
• If your baby doesn’t like an allergen food the first time they try it, don’t force them. But try again every couple of days until they get used to it. You can also find ways to disguise the allergen, such as mashed potato mixed with some milk or feeding them products that have milk in it, like cheese. Just avoid mixing more than one new allergen together at a time.
• When your baby has eaten a new allergen, keep watch over them for the next two hours to check if there are symptoms of an immediate allergic reaction. If there is no sign of an immediate allergic reaction, continue to give your baby that new allergen about three times a week to help their immune system develop a tolerance, then move onto another allergen the following week.

If your baby has an immediate allergic reaction to an allergen, stop giving them the food and contact your healthcare provider for guidance. If your baby’s immediate allergic reaction is severe (which is very rare) and their airways or breathing is impacted, call emergency services. Here are some signs that your baby’s breathing might be impacted:

• Swelling of their throat and tongue.
• Difficulty breathing or if they’re breathing very fast.
• Difficulty swallowing or a hoarse cry.
• Wheezing, coughing or noisy breathing.

If you’d like more details on weaning, read my blog, ‘Is your baby ready for weaning? Signs and considerations.’ It’s natural to feel nervous about introducing allergens to your baby’s diet, but it’s the safe and recommended thing to do, so you can rest assured. Your healthcare provider is always on hand to answer any questions or concerns you have along the way as you help strengthen your baby’s immune system with weaning.

Useful links for parents:

Irish Food Allergy Network: https://www.ifan.ie/

Children’s Health Ireland: https://www.childrenshealthireland.ie/list-of-services/allergy/

This content is for information purposes only and is not intended or implied to be a substitute for professional medical advice, diagnosis, or treatment. Always seek advice from your GP or an appropriate medical professional if you have concerns about your health, or before commencing a new healthcare regime. If you believe that you are experiencing a medical emergency call 999 / 112 or seek emergency assistance immediately.

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