Introducing Allergens To Baby

Weaning onto solid foods is exciting but can also be daunting especially if you’re worried about introducing allergens to baby.

This is a real concern for many parents, after all how will you know if your baby is going to be allergic to a food till you try them? And could a reaction be life threatening? It’s understandably scary stuff!

However, the vast majority of babies will be fine. Food allergy – although well known about – is actually extremely rare.

A mother nursing her baby, a critical phase for protecting against allergens baby may encounter

Can I protect my baby from developing food allergy?

There’s evidence suggesting that exclusively breastfeeding for the first 4-6 months has a protective effect against your baby developing food allergies.

Breast milk is thought to play a crucial role in safeguarding your baby against allergens your baby might be exposed to. It’s currently recommended to introduce food allergens alongside breastmilk to leverage its protective effect.

Avoiding eating certain foods while breastfeeding won’t make a difference, so there’s no need to restrict your diet.

However infant formula does not offer the same protection and may even increase the risk of your little one developing a food allergy. 

Some babies have a ‘high risk’ of developing a food allergy and this includes:

  • Babies with moderate to severe eczema or eczema that started in the first 3 months of life
  • Babies who already have a food allergy

If you’re worried about your baby developing a food allergy because an older sibling has one, it’s understandable, but recent studies show that the risk isn’t significantly higher just because of this family link. 

The key issue is often delaying introducing allergens to baby. Delaying can actually increase the risk of your baby developing a food allergy. 

So, it’s important to make a plan for introducing allergens to baby, and especially so if someone else at home has a food allergy, to ensure their safety too.

A baby in a high chair being fed by an adult

Introducing allergens to baby to minimise the risk

How you start solids can vary slightly depending upon whether your baby is at high risk of food allergy or not.

For babies who are high risk

If your baby is at high risk of developing a food allergy, they might benefit from earlier introduction of solids including egg and peanut at 4 months of age to protect against egg and peanut allergy.  

This should only be done with the support of a specialist team and isn’t something to try by yourself at home.  

All foods need to be developmentally appropriate at at 4 months your baby is very young baby and wont have the eating and drinking skills required for standard textures, so at this age babies need very thin purees.

You can feed them all the usual vegetables and fruits foods at the start of weaning as none of these are high risk allergenic foods (despite what you might hear about strawberries or kiwi). Your allergy specialist team will say when it’s the right time for introducing allergens to baby and they’ll start with egg and peanut.

For babies who are not high risk

If your baby is not at high risk of allergy, the best time to start solids is when they’re developmentally ready.

It’s usually around 6 months of age, although some babies get there a little sooner. I have a free online course which helps prepare you for weaning and includes some simple checks to decide if your baby is ready for weaning.

Start with bitter vegetables for the first week or so to help train their taste buds. After that, there’s no need to introduce foods singly unless they’re a common allergen (scroll down for a full list). Go ahead and mix things up a bit; you can create some wonderful flavour combinations.

Nutrition is critical at this stage in your baby’s development so avoid sticking to just fruit and vegetables for weeks on end. They need protein, energy-dense foods and lots of iron after a week or two. You can read more about the critical nutrients needed for babies and the best weaning foods.

A group of babies sitting on a blanket outdoors

For all weaning babies

When introducing allergens to baby, do so one at a time. It’s important to have them all introduced by 12 months of age.

Delaying introduction of these foods beyond 12 months can actually make the likelihood of having an allergy greater.

You do not need to follow any specific order when introducing allergens, unless your little one is at high risk. In such cases, it’s advisable to start with egg and then peanut. After that, you can offer the other food allergens detailed in the list below.

It makes sense to keep a food diary and note any unusual signs and symptoms when offering new foods. Ask your GP to prescribe a small bottle of baby antihistamine if you’re nervous and keep this handy for if your baby does have allergic reactions.

Hard-boiled eggs in a bowl, a common food when considering allergens baby may be introduced to during weaning


When introducing egg, ensure it’s well cooked and the yolk and the white combined. Choose British red lion stamped eggs and make sure that these are not out of date.

Scrambled egg or omelette strips work well or you could try hard boiled egg mixed with a little bit of your baby’s normal milk for more of a puree. Over a week you should aim for your baby to have one small egg, made up of a little bit each day over a few days.

A jar of peanut butter, a common allergenic food that allergens baby may be introduced to during weaning


You mustn’t give your baby whole nuts due to the risk of choking, and peanut butter on a spoon can also pose the same risk as its very thick. 

Puffed peanut snacks like Bamba or Cheeky Monkey, or peanut powder mixed into food, or a small amount of smooth peanut butter warmed and thinned down with some of your baby’s usual milk or hot water are better options. 

You can add this thinned peanut butter to pureed fruits or vegetables. 

You would be aiming to include roughly 1 and a half teaspoons of peanut butter into your little one’s diet in the first week, adding just a small amount over a few days.

If your baby tolerates these foods without an allergic reaction, continue offering them regularly as part of their normal diet. This repeated exposure has a protective effect.

A baby self-feeding in a high chair

Other allergens baby should introduce

You can then start to offer the other common food allergens alongside other tolerated foods. Just offer one at a time (no more frequently than one new allergen per day) and just ¼ to ½ teaspoons worth, so that if your baby does react you know which one was the culprit.

The UK’s Food Standards Agency has listed the top 14 common allergens

  • Celery
  • Cereals containing gluten such as wheat, rye, barley and oats
  • Crustaceans (shellfish) such as crab, prawns and lobster
  • Eggs
  • Fish
  • Lupin (a type of flour that can be used in bread)
  • Milk
  • Molluscs (shellfish) such as oyster and muscles
  • Mustard
  • Peanuts
  • Sesame
  • Soybeans
  • Sulphur dioxide and sulphites (commonly used as a preservative in dried apricots and desiccated coconut)
  • Tree nuts such as almond, cashew, walnuts, brazil nuts, pecans, hazelnuts

Again, if your baby is fine with them, continue offering them regularly as part of their normal diet to benefit from the protective effect of repeated exposure.

A calendar with a doctor's appointment marked, a common step for parents managing allergens baby might encounter

What else you can do if you’re very concerned?

You may want to consult an allergy specialist doctor before starting. To arrange a referral, you can visit your GP. An allergy specialist doctor may suggest carrying out allergy testing first if you have a strong family history of allergy.

If you’re still unsure on how to introduce common food allergens I have a low cost online course called ‘Introducing Allergens Safely’ which walks you through what to introduce and how to introduce them.  It even includes cooking demonstrations so you know that you’re getting it right.

A baby with visible facial redness, potentially indicative of a reaction to allergens baby has been exposed to.

What symptoms might I see when introducing allergens to baby?

Allergies can be immediate or delayed. The symptoms you might see immediately are vomiting, hives or a red rash, swelling in the mouth or throat, wheezing, shortness of breath, and difficulty breathing. 

Delayed reactions are more likely to be colic-like symptoms, eczema, vomiting, diarrhoea, constipation, a stuffy, itchy nose and poor weight gain and growth.

If your baby experiences breathing difficulties this is a medical emergency so dial 999 for help.

Think about keeping an antihistamine at home. Most indicate they are not suitable for under 1’s so emergency team will instruct you on how much to give.

A mother comforting her baby

If my baby has a reaction how do I manage the allergy?

Food allergies are managed by avoiding the food that’s caused the reaction. If this is milk, wheat, soya or egg or a combination of several foods you will need to see a dietitian who specialises in children. You can find a private dietitian.

Working with a dietitian is crucial because finding the right balance of nutrients for growth and development in the first 2 years of life can be challenging on a restrictive diet.

A dietitian will also help you avoid all traces of the allergenic food and advise on how to safely reintroduce allergens when the time is right, to see if your child has outgrown the allergy.

Sarah Almond Bushell MPhil, BSc (Hons) RD MBDA - Registered Dietitian & Children’s Nutritionist
Sarah Almond Bushell MPhil, BSc (Hons) RD MBDA – Registered Dietitian & Children’s Nutritionist

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meet Sarah

I’m Sarah, a Registered Dietitian, Children’s Nutritionist and mummy from East Sussex. My blog is to guide & inspire you with information about weaning, nutrition, food and toddler feeding. Learn more about me here.

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