Introducing Allergens to Baby – how to minimise the risk of an allergic reaction

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Weaning your baby onto solid foods is exciting but can also be daunting. Worrying about food allergy is a real concern for some parents when you start weaning your baby.

How will you know if your baby is going to be allergic to food? Could they have a life threatening reaction? It’s scary stuff!

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

Having said that a child is more likely to develop an allergy (during weaning or at any time during their life) if they have a parent or sibling who has an allergic condition whether that be asthma, eczema, hay-fever or a food allergy.

Can I protect my baby from developing a food allergy?

There is medical evidence that suggests breastfeeding exclusively for the first 4-6 months (which means no bottles of infant formula at all) has a protective effect against your baby developing food allergies. (1)

It is also thought that breastmilk plays an important role in protecting your baby against allergens and it is currently recommended to introduce the food allergens alongside breastmilk to take advantage of it’s protective effect. (1)

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

Feeding your little one with infant formula does increase the risk of your little one developing an allergy. (2)

If your baby already has an allergy or if mum, dad or their sibling has asthma, severe eczema, hayfever or an allergy, your little one is at a slightly greater risk of developing an allergy (to anything) too. But it’s important to remember that your little one doesn’t inherit a specific allergy. If Dad has a peanut allergy, it means that your baby is at high risk of developing any allergic condition, not necessarily a peanut allergy.

Introducing allergens to baby to minimise the risk

How you start solids depends upon whether your baby is at high risk or not. (3)

For Babies Who Don’t Have Parents Or Siblings With Allergies, Eczema Or Hay-Fever

Start introducing solid food to your baby in the normal way. You should be starting at around 6 months when your baby is developmentally ready click here for a FREE download on three checks you can do with your baby at home to see if they are ready. 

Start with bitter vegetables to help train their taste buds. After that, there’s no need to introduce foods singly (this is old information), 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.

For Babies Who Have Severe Eczema Or Have A Parent Or Sibling With Asthma, Eczema, Allergy Or Hay-Fever

Start when your baby is developmentally ready which is usually around 6 months (26 weeks).

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).

Don’t forget the importance of introducing other foods in order for them to be properly nourished with those critical nutrients.

The advice is to introduce foods containing allergens, one at a time between 4 months and 12 months of age alongside a normal weaning diet. Delaying introduction of these foods beyond 12 months can actually make the likelihood of having an allergy greater. (4)

It is advisable to start with egg and then peanut, after that the other food allergens detailed on the list below can be offered. 

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 and keep this handy too, this is quite safe to give little ones and useful if your baby does have a reaction.

Food allergies in babies by Sarah Almond Bushell - the Children’s Nutritionist


When you’re introducing egg to your baby, it should be cooked and the egg and the white should be offered together.

Choose British red lion stamped eggs and and make sure that these are not out of date. Something like 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 style meal. Over a week you should aim for your baby to have had one small egg, made up of a little bit each day over a few days. (5) 


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. Puffed peanut snacks, 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. (5)

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.


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 food 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 dessicated 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.

I’m very worried about this, is there anything else I can do?

If you are very worried you may want to seek advice from an allergy specialist doctor before starting, you can see your GP to arrange a referral. 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 food allergens I have a mini 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.

What symptoms might I see?

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.

If you have an antihistamine at home, the emergency team can instruct you on how and how much to give.

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 please ask to see an NHS dietitian who specialises in children. You can also see a dietitian privately; my team offer private consultations via zoom for people anywhere in the world.

Seeing a dietitian is extremely important as getting the right balance of critical nutrients needed for growth and brain development in the first 2 years of life can be a challenge.

A dietitian will also help you avoid all traces of the allergic food and advise on how and when to reintroduce it safely to see if your child has grown out of the allergy.

Further Information

If you’ve found this post useful and want to know more about your baby’s nutrition and growth during their first year of life, I have an online course called Happy Healthy Weaning. Follow the link to find out more.

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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