Food Allergies and how to prevent peanut allergy in babies

Allergies in babies are really common, but it can be worrying when your baby is poorly, and some symptoms from allergic reactions to food can be alarming to parents. Many children do grow out of allergies eventually, but some may experience more severe allergic reactions that need medical attention.

We share insights from our research and expert advice on how you can manage symptoms of a food allergy, what symptoms to look out for, which foods are most commonly related to food allergies, and what the difference is between a food allergy and a food intolerance.

We also have information from a new study about how you can actually prevent peanut allergies in children by feeding them peanuts from an early age!

What is a food allergy?

A food allergy is when your baby’s immune system has a bad reaction to what is usually a harmless food, and tries to fight it by producing an antibody called Immunoglobulin E (IgE). It’s the production of these antibodies that causes the distinct symptoms.

"It’s thought five to six per cent of children under the age of three develop a food allergy in the UK," says Dr Carina Venter, an Allergy Dietitian for the Infant & Toddler Forum. "The verdict is still out as to why some people develop food allergies, but we do know that genetic factors play a role."

Allergic reactions are often mild, but they can be very serious. if your child is experiencing some mild symptoms, they may actually be experiencing food intolerance, which can produce mild symptoms similar to some food allergies.

What's the Difference Between a Food Allergy and a Food Intolerance?

According to the NHS a food intolerance is when you have difficulty digesting certain foods or ingredients in food. They say, "It's not usually serious, but eating the food you're intolerant to can make you feel unwell."

Carina adds: "Food intolerances are different to food allergies because they’re not caused by an immune system reaction." She says, "This means they’re not in most cases life threatening, but they can cause uncomfortable symptoms such as bloating and diarrhoea."

Common symptoms of a food intolerance include:

Other symptoms may include:

Symptoms of food intolerence can last for a few hours or days.

What are the symptoms of a food allergy?

Allergic symptoms can be “immediate” or “delayed” in nature. If your baby or toddler is allergic to a food, the symptoms could appear within two hours.

According to the NHS, common symptoms of a food allergy include:

In more serious cases, your child may go into anaphylactic shock, which causes breathing difficulties, swelling of lips and tongue and wheezing. They may get hives, itchy skin, vomiting and sudden diarrhoea. "Your baby may also suffer a more delayed reaction, which can include stomach pain, reflux, bloating and wind," says Carina.

Testing and diagnosis for food allergies in children

Your GP may refer your baby to a paediatrician or allergy clinic. "For some food allergies, there are skin prick tests to check levels of antibodies that your body produces during a reaction," says Carina. In skin testing, a small amount of extract made from the food is placed on the back or arm. If a raised bump or small hive develops within 20 minutes, it indicates a possible allergy.

Carina says, "Most children are diagnosed by a trial elimination diet, where you’ll be asked to completely avoid the suspect food for a certain time, which is then followed by a food challenge, where the food is introduced back into the diet to check the reaction."

Common food allergies

When it comes to actual food allergies, as opposed to food intolerences, reactions can be immediate and quite serious, while others appear a few hours or even days later.

Here are the most common food allergies in babies and toddlers:

Egg allergy in children

Egg allergy is caused by an allergic reaction to egg protein that's found mostly in the egg white, but also in the yolk. It is common in children under 5 years and you may notice some mild symptoms during early weaning – like redness or swelling around the mouth, or your baby may vomit within two hours after eating and develop a tummy ache. Diarrhoea is also likely. Thankfully, it is rare for egg allergy to develop in adulthood.

If you're feeding eggs for the first time and feeling worried, it can be helpful to know that the more the egg is cooked or processed the less likely it is to cause a reaction. You can also feed a small amount at a time to reduce the chances of a more severe allergic reaction. Severe reactions to egg are rare, but if your little one develops a cough, has difficulty breathing, or you notice an asthma-type wheeze, or worse, anaphylaxis, you should seek professional medical advice and support immediately.

Cow's milk allergy in children (CMA)

Cow's milk allergy, or CMA, is one of the most common childhood food allergies, and according to Allergy UK around seven per cent of babies under one are affected. They say it's an immune system response to certain proteins found in cow's milk, often casin and whey. This is different to lactose intolerence, which is the inability to digest lactose, or milk sugar. Most children do grow out of this though.

If your child is allergic to cow's milk you will either notice symptoms immediately, or within two hours, but they may also experience a delayed reaction up to 72 hours later, so keep an eye on your little one when feeding cow's milk for the first time during weaning. Look out for skin reactions, digestive problems, hay fever-like symptoms or eczema that doesn't improve with treatment.

Nut allergy in children

If you have a weaning baby and you're feedling them nut butters or foods that contain nuts, you may notice that they have an allergic reaction. Peanut allergy is the most common, but your baby could also have a reaction to other tree nuts such as almonds, brazil nuts, cashews, hazelnuts, macadamias, pecans, pistachios and walnuts.

They contain proteins that can cause an allergic reaction in up to three per cent of children, according to the Royal Children's Hospital in Melbourne. They say that reactions are usually mild, but they can also be a common cause of anaphylaxis (especially cashews), the most severe and potentially life-threatening form of allergic reaction.

What can you do about a food allergy?

Thankfully, it’s become easier to manage food allergies and intolerances due to food labelling and the wide-range of “free-from” products now available.

Your child may grow out of their allergy, but it can depend on what they are allergic to. It’s more common to outgrow a cow's milk and egg allergy than it is to outgrow a peanut allergy. More recently, however, new research has shown that you may be able to prevent your child from developing an allergy to peanuts in the first place!

New research preventing peanut allergies in children

A new NIH study has found that by introducing peanuts in infancy, you can prevent peanut allergy later on all the way into adolescence. They have found that the protection lasts no matter how often children eat peanuts then throughout their childhood.

The NIH Study found that "Feeding children peanut products regularly from infancy to age five years reduced the rate of peanut allergy in adolescence by 71 per cent, even when the children ate or avoided peanut products as desired for many years."

Participants in the trial regularly consumed peanut products from weaning through to five years of age, with the control group avoiding peanut products during this period. Findings showed that early introduction reduced the risks of peanut allergy at five years by 81 per cent.

Participants were then asked to avoid eating peanut products between the ages five to six years, and findings showed that those who had eaten peanut products during their earlier years remained protected from peanut allergy at age six. The study continued to monitor whether the protection lasted, and it did, no matter how frequently peanut products were consumed later on.

How to reduce the risk of peanut allergy

If you want your child to have the opportunity to enjoy peanut products without the risk of developing an allergy, which can be life-threatening, introducing peanut products early on, preferably during weaning, is a really good idea, according to the above research. Gideon Lack, professor of paediatric allergy at King’s College London via The Guardian says, "I strongly recommend that babies are introduced to peanuts by four months if they have eczema and by six months if they don’t have eczema". This is because if your baby has eczema they may be more prone to developing peanut allergies.

How to introduce peanuts to babies when weaning

Baby & Child Nutritionist Charlotte Stirling-Reed shares with us her expert advice on how to introduce peanuts to your weaning baby. She says:

"You can start to introduce peanuts to babies right from the start of your weaning journey, around 6 months, or when your baby is developmentally ready. In some cases, if your baby is at higher risk of developing a food allergy, you may be advised to start weaning earlier and to introduce peanuts, or other allergens. This should always be discussed with a qualified health professional who is familiar with your baby’s allergy history.

"When it comes to HOW to introduce peanuts, the easiest way is to offer a tiny amount (around ¼ of a teaspoon) of smooth, no added salt, peanut butter, either thinned down with some breast/formula milk or mixed in with another food they have already had - e.g. fruit or veg. Alternatively, you could also use very finely ground peanuts or peanut flour (again a tiny amount), mixed in with another food they have had. It’s important to make sure that you’re not offering any other new foods along with the peanut butter, to rule out any possible reaction being due to another food.

"When you FIRST offer peanut butter to babies when weaning, start by offering a very small amount - roughly a quarter/half teaspoon. If there is no reaction, you can gradually increase the amount over the next two to three days or simply try again with a slightly bigger amount a few days later.

"Once you have successfully introduced peanut into your baby’s diet with no reaction, it’s important to keep it in their diet regularly and you can offer it in larger amounts, in order to maintain their tolerance to it. Ideally, aim to offer thinned peanut butter one to two times per week. Some of my favourite ways to offer peanut butter are to mix it in with yoghurt, porridge or cereal, spread it very thinly on toast, or even offer it as part of a savoury curry/stir fry sauce!

"When it comes to offering toddlers and older children peanuts, they shouldn’t be offered whole nuts until around the age of five, due to the potential choking risk. Opt for smooth peanut butter to avoid any large lumps, and if you’re grinding them at home, make sure they’re finely ground with no big pieces left!"

How quickly will a baby react to peanut butter?

You might be nervous about introducing your baby to peanut products for the first time. The NHS advises to make sure they are well and that any eczema is well-controlled. You should be at home and be able to observe your baby for at least two hours after they have eaten the food containing peanuts, as this is usually when any potential allergic reaction to the peanuts will occur.

Most importantly, do not feed whole peanuts to your baby as this is a choking hazard. This includes coursely chopped peanuts or chunky peanut butter if your child is under five years. As Charlotte has described, peanuts should either be ground finely with no lumps and added to food. Alternatively, you can try smooth peanut butter.

Signs of peanut allergy in baby

Mild to moderate signs to look out for include:

If your baby has a more serious allergic reaction they may go into anaphylactic shock and the following symptoms will be present:

When to see your GP

See your GP if your baby has any immediate reactions to food. "This is especially the case if your baby or toddler has an anaphylactic shock," says Carina. Bad cases of diarrhoea and vomiting should also be looked into, so go straight to your GP if this happens.

About the experts

Dr Carina Venter is an Assistant Professor of Paediatric, Section of Allergy and Immunology at the University of Colorado. She is the first dietitian with a faculty position in Allergy and Immunology in the USA, according to Southampton University She is also is an allergy dietitian for the Infant & Toddler Forum.

Gideon Lack is a professor of paediatric allergy at King’s College London. Professor Gideon Lack joined King’s in 2006 as Professor of Paediatric Allergy and Head of the Children’s Allergy Service at Guy’s and St Thomas’ NHS Foundation Trust. He is also a clinical lead in adult and paediatric allergy. He has established two of the nation’s five paediatric allergy centres and is a co-founder of the Allergy Academy at King’s.

Charlotte Stirling-Reed is “The Baby & Child Nutritionist” and is a Registered Nutritionist with the Association for Nutrition. Charlotte is also an author and mum to little foodies Raffy and Adaline, and owner of consultancy, SR Nutrition. It’s her mission in her work to give parents confidence in feeding their children.

About the author

Proud aunt to her teen niece, Zara Mohammed is a Digital Writer for Mother&Baby. She has 10 years freelance writing experience creating lifestyle content for various platforms, including pregnancy, women’s health, parenting, child development and child mental health, plus lots of fun seasonal family articles and celebrity news.