Weaning allergens: how to introduce allergens to your baby while weaning

When your baby is ready to move on to solid foods, you might be wondering whether they have any food allergies and how to introduce allergens to your baby as they wean.

From what food allergies are to how to spot the signs and symptoms and managing weaning allergens in your baby’s diet, we’ve got you covered so you can enjoy happy and healthy mealtimes.

A food allergy is when the body reacts to certain foods¹. They usually occur because your baby’s immune system mistakes a particular food for a threat and goes into defense mode to protect their body and health. Most allergic reactions are mild but can be more serious for some people.

Your baby could be more likely to have a food allergy if²:

• They already have a diagnosed allergy
• They have eczema
• There’s a family history of allergies (e.g. food allergies, eczema, asthma or hay fever)

If that’s the case, you might need to be a little more careful when introducing allergens to your baby, so talk to your GP or health visitor for advice on how best to do this².

If your baby has a food allergy, you’ll probably find that the symptoms will come on quickly – usually within a few minutes of eating the allergen².

If your baby is having an allergic reaction to something they’ve eaten, you might notice²:

• Sneezing
• A blocked or runny nose
• Red, itchy or watery eyes
• Wheezing and coughing
• A red, itchy rash
• Vomiting, diarrhoea or tummy pain
• Worsening asthma or eczema symptoms

Most allergic reactions have mild symptoms, but sometimes they can cause a more serious reaction known as anaphylaxis or anaphylactic shock.

Symptoms of anaphylaxis include swelling around the lips and face and problems breathing. If you see any of these symptoms in your baby, it’s very important to seek emergency medical treatment².

If your child reacts to an allergen while weaning, it’s best to visit your GP to confirm that they have a food allergy. If they do, your GP will be able to give you advice on how to manage it, whether any tests or elimination diets are necessary, and how you can introduce any baby allergens back into their diet.

To make sure that your baby is getting all of the nutrients they need, it’s not advisable to cut certain foods from your own or your child’s diet without advice from a healthcare professional.

In addition to the above, you’ll need to pay close attention to the labels on the foods you buy when doing your weekly shop - you can find more on this below.

Many foods can cause an adverse reaction, but some allergens are more common than others.

Take a look below for a handy list of potential food allergens that you might want to introduce slowly and one at a time into your baby’s weaning diet²:

• Cow’s milk
• Eggs - always choose eggs with a Red Lion stamp
• Gluten - this includes wheat, barley and rye, and other oats that don’t have a gluten-free label
• Soya
• Shellfish. If your baby gets a taste for shellfish, make sure that it’s fully cooked through 
• Fish
• Nuts and peanuts. Nuts can be a choking hazard when served whole under 5 years of age³, so be sure to serve them finely ground or as a nut butter when weaning your baby
• Beans, lentils and peas
• Sesame and other seeds. Again, make sure these are finely ground before giving them to your little one
• Celery
• Mustard
• Sulphur dioxide, which is sometimes used as a preservative in certain foods such as dried fruits and vegetables 

Once your baby is 6 months old, they’ll be ready for their first tastes of solid food⁴. Once they’re used to eating a few new fruits and vegetables and are getting used to various flavours, you can start introducing new tastes and textures - this includes some of the potential weaning allergens in the list above².

Here are our top tips for introducing allergens to your baby⁶:

• Choose a day when your little one feels well and in good spirits. For example, make sure they’re not under the weather with a cold that could be making them fussy. 
• Introduce one allergen at a time in very small amounts to help narrow down the cause of any reactions.
• Keep a symptom tracker to help you remember what foods you’ve introduced and how your little one reacted.
• If your baby doesn’t react to the allergen, great! Keep offering it to them in gradually bigger amounts as part of their normal weaning diet.
• If your baby does have a reaction, stop feeding them the allergen and talk to your GP or healthcare professional for advice.

Cow’s milk protein allergy is one of the most common allergies in babies and children⁷. If your baby has been diagnosed, your healthcare professional will have provided specific guidance on managing this, depending on the type of cow’s milk allergy your little one has.

Weaning a baby with a cow’s milk allergy is just like weaning any other baby, except that you should avoid any foods that contain cow's milk⁸. You should still introduce other allergens in small amounts as usual but be aware that your little one might be more likely to have allergies to other foods too, so keep an eye out for any symptoms².

If you’ve got any concerns, talk to your GP or other healthcare professional who can provide more advice about introducing baby allergens safely whilst ensuring that your little one gets all the nutrients they need to stay happy and healthy⁹.

While some studies have found that exclusively breastfeeding could protect babies from developing some food allergies, overall, the evidence is mixed¹⁰.

If you’re breastfeeding, you don’t need to avoid common allergens unless you’re allergic to them yourself². However, if your baby is diagnosed with a cow’s milk protein allergy and is exclusively breastfed, you might be advised by your healthcare professional to eliminate cow’s milk from your diet to see if their symptoms improve⁹.

If your baby does have a food allergy and needs to avoid certain allergens in their diet, you’ll need to get well-acquainted with the labels on the food you buy. Here’s what to look out for.

The Food Standards Agency has strict guidelines about how manufacturers label allergens in prepackaged food. This is designed to help you and your family make safe choices about the food you eat.

Prepackaged food labels must include a list of ingredients, with any common allergies listed in bold to make it easy to spot¹¹. 

Some manufacturers also include what’s known as ‘precautionary labelling’. This includes statements like ‘may contain traces of…’ when there’s a risk of cross-contamination from other foods made in the same factory (gluten and nuts are good examples)¹¹.

Depending on how severe your baby’s allergy is, you may or may not need to avoid foods that have these precautionary labels, and it’s best to speak to your GP about how cautious you need to be when it comes to avoiding potential baby allergens¹¹.