Baby allergens

Learn more about food allergies in babies and find a helpful list of food allergens, and how to introduce allergens to babies when weaning.

Should you worry about food allergies when your baby is ready to start solids?

In the United Kingdom, the Department of Health recommends starting solids when your baby is around 6 months of age or when he/she is developmentally ready.

The general advice is to start offering your baby a wide variety of foods, starting with fruit and vegetables.

But what about some of the common food allergens and when should you introduce them to your baby?

This article will explore the most common food allergies in children and share ways of introducing food allergens safely to your baby.

What is food allergy?

As per NHS England, food allergy is when the baby’s immune system behaves unusually to a specific food.

The body’s immune system mistakenly treats proteins in food as a threat.

Although food allergies can be mild, some reactions can be very serious.

Your baby is more likely to develop a food allergy if another member of the immediate family (parents or siblings) has a family history of food allergy, asthma, hay fever or eczema.

Food allergy symptoms and signs in a baby

With a food allergy, the symptoms are usually evident within minutes or seconds.

An allergy is when the immune system gets a bit confused by reacting to an allergen in the food and builds antibodies to attack it.

Signs of food allergies in babies to look out for include:

  • Sneezing
  • Runny or blocked nose
  • Red, itchy or watery eyes
  • Wheezing and coughing
  • Red, itchy rash around their mouth, nose, cheeks
  • Swollen lips, eyes or face
  • Vomiting
  • Diarrhoea
  • Worsening of existing asthma or eczema
    - Most symptoms of food allergy are mild.
    - Very occasionally your baby may experience a severe reaction called anaphylaxis.
    - Anaphylaxis is a medical emergency and requires urgent treatment.
    - Signs and symptoms include:
  • Severe respiratory distress, such as difficulty breathing
  • Wheezing
  • Floppiness or losing consciousness

What to do if your baby has a food allergy

If your baby has a food allergy or eczema, or if you have a family history of allergies you may need to be more careful when introducing complementary foods. Make an appointment with your doctor or health visitor so that they can provide advise on how to manage the introduction of complementary foods.

Food allergen list to help you manage your baby’s allergy

Any of the following 14 foods can trigger an allergic reaction in babies but this is not an exhaustive list.

Always monitor your baby when introducing new foods for an allergic reaction to other food allergens.

  • Cow’s milk and other milk-based products
  • Eggs (choose eggs with the red lion stamp and cook till both egg white and yolk are solid)
  • Fish and molluscs
  • Gluten (including foods that contain wheat, rye, barley and oats)
  • Nuts & peanuts (offer ground or crushed only. Do not give whole nuts of any kind to children under 5 years as they pose a choking risk)
  • Soya
  • Shellfish (serve cooked)
  • Sesame and other seeds (serve ground or crushed only)
  • Mustard
  • Lupin
  • Sulphur dioxide
  • Celery

You should introduce all of the above common food allergens one at a time.

Introducing allergens to your baby

Once your baby is comfortably enjoying vegetables and fruit, you can start introducing the common food allergens anytime from the age of six months.

It’s important to introduce the common food allergens one at a time.

Breakfast is the best meal of the day to try a common allergenic food.

Offering it earlier in the day makes it easier to monitor your baby closely for a few hours following controlled exposure to a food allergen.

Most babies who go on to develop an allergic reaction will do so within a few minutes to two hours of consuming the food.

For this reason, choose a day when your baby is well.

Start with a small, cooked portion of the food allergen and increase the portion sizes over a few days.

This is the recommended way of introducing food allergens to ensure that you can easily spot signs of food allergies in babies.

Once your baby tolerates a full portion size, continue to offer the tolerated food as part of your baby’s diet to minimise any future risk of developing a food allergy.

Baby weaning and allergens

As a rule of thumb once your baby is tolerating fruit and vegetables you can start introducing any of the food allergens described earlier in this article.

For an extended list of baby weaning foods to include and avoid see ‘Baby Weaning - Foods To Include And Avoid’.

Introducing food allergens to babies diagnosed with cow’s milk protein allergy

If your baby has been diagnosed with cow’s milk allergy, your allergy team will be your first point of contact for individualised advice.

Following the results of the EAT study, it is now evident that introducing common food allergens early can reduce the risk of developing further food allergies.

If your baby has been diagnosed with cow’s milk allergy, you may be advised to introduce eggs and peanuts anytime from 6 months of age.

Early introduction can help prevent allergies to these food allergens.

Your paediatric dietitian or allergy team may recommend offering these foods once your baby has established first weaning foods like fruit and vegetables.

It’s essential that the introduction of common food allergens like eggs and peanuts are not  unnecessarily delayed beyond 12 months of age.

Always seek personalised advice from a healthcare professional if you are unclear about how to introduce these food allergens safely.

Food allergies in breastfed babies

Although some studies suggest that exclusive breastfeeding could protect babies from developing food allergies, the overall evidence is mixed.

Despite this, there are various benefits to breastfeeding until 6 months and beyond.

These include reduced risk of upper respiratory tract infections, infectious diarrhoea requiring hospital admissions and higher IQ scores in later childhood.

Food allergens such as cow’s milk, white hen egg and peanut do cross over to breastmilk from the maternal diet.

Therefore breastfed babies can also develop food allergies.

Where possible, continue to breastfeed your baby whilst introducing the common food allergens.

Egg allergy in babies

When first introducing eggs, start with a small portion of well-cooked eggs (preferably choose eggs with the red lion stamp).

If your baby shows signs of an egg allergy after consuming the cooked egg, stop offering eggs and any foods containing eggs.

Speak with a healthcare professional for further advice.

Understanding allergen labels

How are allergens shown on a label?

The Food Standards Agency stipulates that if a packaged food item contains any of the 14 food allergens, it must be clearly labelled on the food packaging.

In the UK, all food packaging must include an ingredient list.

If a food item contains a food allergen, this will be highlighted in bold, in contrasting colours or underlined.

Allergenic ingredients like tofu will be clearly labelled as containing soyor foods containing whey will be labelled as a source of milk.

This makes spotting food allergens in packaged foods more manageable.

May contain allergen labelling

Some manufacturers will also use the statement ‘may contain traces of’ on their packaging.

This is a type of precautionary allergen labelling to highlight a potential risk of cross-contamination.

What this means is that the food item has been prepared in the same factory or tray line as another food containing one of the food allergens.

Speak to your paediatric dietitian about how this impacts your child with an existing food allergy.


Weaning or starting complementary foods is an exciting time for you and your little one. 

Although some babies will go to develop a food allergy, it’s important to introduce the common food allergens as part of your baby’s weaning plan. 

Current weaning guidelines recommend that the common food allergens are offered anytime from 6 months to 12 months. 

The food allergens should be introduced one at a time so that you can quickly identify an allergic reaction. 

Seek advice from your paediatric dietitian or healthcare professional if you need personalised advice.

  1. NHS (2022). Start for life.  Weaning.
  2. Muraro, A et al. EACCI Food Allergy and Anaphylaxis Guidelines. Primary prevention of food allergy. Allergy, 2014;69(5):590-601.
  3. NHS UK 2022.  Food Allergies in Babies & Young Children.
  4. Halken, S, Muraro, A, de Silva, D, et al; European Academy of Allergy and Clinical Immunology Food Allergy and Anaphylaxis Guidelines Group. EAACI guideline: Preventing the development of food allergy in infants and young children (2020 update). Pediatr Allergy Immunol. 2021; 32: 843– 858.
  5. Martín-Muñoz MF, Pineda F, García Parrado G, Guillén D, Rivero D, Belver T, Quirce S. Food allergy in breastfeeding babies. Hidden allergens in human milk. Eur Ann Allergy Clin Immunol. 2016 Jul;48(4):123-8. PMID: 27425167.
  6. ​​Perkin MR, Logan K, Marrs T, Radulovic S, Craven J, Flohr C, Lack G; EAT Study Team. Enquiring About Tolerance (EAT) study: Feasibility of an early allergenic food introduction regimen. J Allergy Clin Immunol. 2016 May;137(5):1477-1486.e8. doi: 10.1016/j.jaci.2015.12.1322. Epub 2016 Feb 17. PMID: 26896232; PMCID: PMC4852987.
  7. Food Standards Agency 2022.  Allergen Labelling for Food Manufacturers.
  8. Greer FR, Sicherer SH, Burks AW; COMMITTEE ON NUTRITION; SECTION ON ALLERGY AND IMMUNOLOGY. The Effects of Early Nutritional Interventions on the Development of Atopic Disease in Infants and Children: The Role of Maternal Dietary Restriction, Breastfeeding, Hydrolyzed Formulas, and Timing of Introduction of Allergenic Complementary Foods. Pediatrics. 2019 Apr;143(4):e20190281. doi: 10.1542/peds.2019-0281. Epub 2019 Mar 18. PMID: 30886111.

Last reviewed: 24th March 2022
Reviewed by Nutricia's Medical and Scientific Affairs Team

Bahee Van de Bor

Bahee Van de Bor

Bahee Van de Bor is a registered paediatric dietitian with over 16 years of clinical experience. Her areas of expertise include irritable bowel syndrome, picky eating and cow’s milk protein allergy.

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