A Guide to Food Allergies in Babies

As a parent, you’re probably well-versed in the ins and outs of caring for your little one. But when it comes to food allergens, it can be difficult to know what symptoms to look out for — particularly when reactions vary from a mild reaction to a severe allergic reaction.

Cow’s Milk Protein Allergy (CMPA), soy allergy, egg allergy and peanut allergy are among the most common food allergies affecting babies and young children. We’ve explored what the different types of allergies are, some symptoms to watch out for, and how you can access support and medical advice if you suspect your baby has a food allergy.

[Article updated December 2025]

Most common allergies in babies

Cow’s Milk Protein Allergy (CMPA)

​CMPA is one of the most common food allergies in infants, with around 2–7% of babies suffering from some form of reaction. Symptoms can range from mild skin reactions like eczema, itching or hives, to more severe reactions such as vomiting, diarrhoea, wheezing or difficulty breathing.

CMPA can be IgE-mediated (immediate) or non-IgE-mediated (delayed), which is why symptoms can sometimes be difficult to link directly to feeding, particularly in breastfed babies.

Soy Allergy

Soy allergy is also relatively common in babies but slightly less prevalent than CMPA with approximately 1–2% of children affected. While many parents opt to switch their baby onto soy formula if they suspect CMPA, this may not be a suitable solution if your baby has a soy allergy as well.

Symptoms may include mild skin rashes or hives, vomiting or diarrhoea, coughing or wheezing.

Egg Allergy

Egg allergy also affects around 1–2% of babies and young children under five years old. Symptoms can occur the first time egg is introduced or after repeated exposure.

Common symptoms include:

• Skin reactions such as rashes or hives
• Vomiting or diarrhoea
• Coughing or wheezing
• Sneezing or watery eyes
• Swelling around the mouth
• Anaphylaxis
• In some cases, a runny nose with no other visible symptoms

Many babies with egg allergy are later able to tolerate egg in baked forms, often with guidance from a healthcare provider using an egg ladder.

Peanut Allergy

Peanut allergy is one of the most widely recognised food allergens and can cause reactions ranging from a mild reaction to a life-threatening reaction. While peanut allergy is less common in babies than CMPA or egg allergy, it is more likely to persist into later childhood.

A peanut allergy occurs when the child’s immune system reacts to peanut protein, sometimes after very small amounts or accidental exposure to peanut residue.

Symptoms of a peanut allergy may include:

• Hives or skin redness
• Swelling of the lips, tongue or face
• Vomiting or abdominal pain
• Coughing, wheezing or difficulty breathing
• Drop in blood pressure
• Signs of anaphylaxis

A severe reaction requires immediate emergency care. If your baby shows signs of trouble breathing after exposure to a new food or peanut products, swelling of the throat or collapse, seek emergency medical help straight away.

Different types of allergies

One thing that many parents of babies with suspected allergies quickly realise is that it can be very tricky to pinpoint symptoms, particularly if their child is suffering with a delayed reaction or if they’re breastfed.

There are two different types of allergic reactions:

• IgE-mediated allergies, which are immediate reactions where histamine is released into the body
• Non-IgE-mediated allergies, also known as delayed reactions

IgE-mediated reactions

The most common symptoms of an immediate food allergy include:

• Skin reactions such as hives or swelling
• Swelling of the mouth, tongue or throat
• Wheezing, coughing or difficulty breathing
• Abdominal pain, vomiting or diarrhoea
• Dizziness or changes in blood pressure

In rare cases, IgE-mediated reactions can result in anaphylaxis, which is life-threatening and requires emergency care.

Non-IgE-mediated reactions

The symptoms of a delayed food allergy in babies are often less obvious and can occur hours to days later.

These may include:

• Rashes or atopic eczema
• Diarrhoea or constipation
• Vomiting
• Abdominal pain

In babies, delayed reactions may also present as reflux or colic, including excessive or inconsolable crying. This can make these types of allergies more difficult to diagnose.

How to get help

If you think that your baby is suffering from a food allergy, it’s important to get in touch with your GP or healthcare provider. They can give you advice, carry out a physical exam, and refer you to the appropriate medical professional if needed.

You may be referred to:

• A dietitian or nutritionist
• A paediatric clinic or pediatric allergist
• An outpatient clinic for further assessment

In many cases, no immediate testing is needed and symptoms improve once the suspected allergen is removed from the baby’s diet or from breast milk.

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Allergy testing in babies

Most babies with CMPA will not need allergy testing, as symptoms often improve once cow’s milk protein is eliminated.

However, allergy testing may be recommended if:

• Symptoms persist
• The reaction appears immediate
• Multiple food allergens are suspected

Testing options may include:

• Skin prick test
• Blood test measuring IgE antibodies
• Oral food challenge, carried out in a clinical setting under medical supervision

Test results are always considered alongside symptoms and medical history.

Allergies & breastfeeding

Allergies in breastfed babies can be more difficult to identify, as allergens can transfer into breast milk in small amounts.

If you are breastfeeding and suspect a food allergy:

• Keep a detailed food diary of what you eat and symptom diary for your little one
• Avoid removing multiple foods at once without medical advice
• Eliminate suspected allergens gradually and monitor symptoms

Once your baby begins eating solid foods, both their diet and your own may need to avoid the allergen while breastfeeding continues.

Allergies & formula feeding

If your baby has CMPA or a soy allergy and is formula fed, a suitable alternative formula will be required.

Cow’s milk protein allergy is not limited to cow’s milk alone, as other animal milks such as goat’s milk often trigger the same reaction and are not recommended.

Your GP, dietitian or healthcare provider will advise on prescribing a hypoallergenic formula appropriate for your baby’s needs.

Weaning — where to begin?

When starting solid foods and weaning your baby, it’s important to be aware of common allergens and introduce new foods carefully.

The safest approach is to introduce foods:

• One at a time
• In small amounts
• With several days between new foods

You may need to speak to a dietitian or nutritionist to ensure that your baby is getting all the nutrients they need. They will be able to provide suggestions on alternatives for babies who need to avoid specific foods — for example, if your baby needs to avoid milk, you will need to offer them calcium-enriched foods and foods with healthy fats elsewhere in their diet, such as avocado or adding olive oil to mashed potatoes.

In the UK, allergens should always be clearly labelled on food and should be easy to spot as they are written in a bold font. If you are travelling with your baby, ensure that you know the name for the allergens in the country you are travelling in and are aware of how allergens may or may not be labelled on the packaging. When eating out, whether at home or abroad, it’s always best to double check with your server or a manager about allergens. They may be able to prepare a dish differently or separately for you or your baby.

If your baby attends nursery or another childcare setting, you’ll want to make sure that they have been properly informed of their allergy. You may also want to know about their guidelines for children with allergies — for example, they may need to feed them in a separate area to the other children to avoid cross-contamination or provide them with different meals and snacks.

Read more: A Guide to Pregnancy & Parenthood Acronyms

Introducing Peanuts during Weaning

Newer research, including the LEAP study, suggests that early introduction of peanuts may reduce the risk of developing a peanut allergy, particularly in babies with eczema or egg allergy.

Key safety points include:

• Whole peanuts and chunky peanut butter should never be given to babies
• Peanut foods should be smooth and age-appropriate
• Smooth peanut butter can be thinned with warm water or breast milk
• Peanut flour or peanut powder can be mixed into purées

Babies with severe eczema, egg allergy or a higher risk of allergies may need peanut introduction to be discussed with a healthcare provider first.

How to alleviate symptoms

For many babies, cutting out the allergen from their diet or from the mother’s breast milk leads to an improvement in symptoms. For delayed reactions, this may take up to two weeks.

Treatment options may include:

• Antihistamines for IgE-mediated reactions (only with medical advice)
• Emollients or prescribed creams for eczema
• Ongoing dietary management with professional support

Allergy ladders

It can be reassuring to know that many babies outgrow certain allergies, particularly CMPA and egg allergy.

An allergy ladder, such as a milk ladder or egg ladder, allows for gradual reintroduction of the allergen in increasing amounts. This process should always be guided by a healthcare provider.

Some allergens, including peanuts and tree nuts, may require reintroduction only under medical supervision.

Conclusion

Food allergies in babies can feel frightening and overwhelming,  if you’re a parent experiencing them for the first or thirtieth time. The important thing to remember is that there are plenty of medical professionals who can assist you and that there are a lot of alternatives easily available now for your baby. If you’re unsure, always get in touch with your GP who will be able to guide you towards the right support with appropriate medical advice.

If you’re ever unsure, contact your GP or healthcare provider for guidance and support.

Where to find help

NHS Start4Life – Food Allergies & Safe Weaning

Allergy UK