At around 6 months old, your baby is ready to begin eating solid food. Although in most cases this can be a magical (if sometimes messy) adventure, some babies can react badly to certain foods. Read on to learn what exactly a food allergy is, what some common food allergies are, how to spot the symptoms and what to do if your baby has an allergic reaction.

What Are Food Allergies?

An allergy is the immune system's response to something it doesn't like. Things that trigger an allergic reaction are called allergens. For example, some people are allergic to dust or pollen and get itchy eyes or a runny nose when exposed to these allergens. With food allergies, most people react with digestive problems, itching, rashes or breathing problems. Babies who have food allergies usually experience them before the age of 3. The good news is that children often grow out of these early food allergies. Although the causes of food allergies in babies are not fully understood, it is known that if your baby has eczema there’s a higher chance of him or her also developing a food allergy. Luckily severe allergic reactions are rare, but if they do occur it’s important to get treatment immediately. This is why it’s important to know what an allergic reaction can look like and what to do if you suspect your baby has a food allergy.

Signs and Symptoms of Food Allergies

The symptoms of a food allergy, and how soon they appear, depends on the antibodies released into the body when the reaction is triggered. There are three main types of food allergy:

IgE-Mediated Food Allergy

The most common kind of food allergy is where your child’s body – for unknown reasons – releases an antibody called immunoglobulin E (IgE) in response to harmless proteins in the food that has triggered the allergic reaction. The symptoms of this kind of allergy usually appear within a few seconds or minutes after eating the food, and include:

  • A red, raised itchy rash (hives) or just patches of red, itchy skin

  • Sneezing and/or itchy eyes

  • An itchy throat and tongue

  • Swelling of the mouth, throat or other parts of the body

  • Feeling sick or vomiting

  • A tummy ache or diarrhoea

  • Anaphylaxis. In rare cases an allergic reaction can be very severe, with symptoms that include difficulty breathing, speaking or swallowing. This condition is a medical emergency that requires urgent treatment.

Non-IgE-Mediated Food Allergy

Some food allergies act via other cells in your baby’s immune system. These types of food allergies are known as non-IgE-mediated. This kind of allergy is harder to diagnose, and the symptoms may appear later – sometimes several days after eating the food that triggers it. The symptoms can include:

  • Red, itchy (but not raised) skin

  • Cracked, red itchy skin

  • Vomiting and/or diarrhoea

  • Tummy ache

  • Constipation

  • Colic (when your baby often cries inconsolably without any obvious reason)

  • Reflux.

Mixed Allergic Reaction

Sometimes, children or babies show a mixture of IgE and non-IgE symptoms. For example, your little one might have swelling or hives as well as constipation. This could be a sign that your baby has a cow’s milk allergy (CMA). However, only your child’s doctor can make an accurate diagnosis, so if you’re unsure what may be causing your little one’s symptoms seek medical help.

When to Call the Doctor

It’s important to notify your doctor if you see any of the above food allergy symptoms. A doctor might prescribe or recommend an antihistamine medicine to help relieve the symptoms of a mild allergic reaction.

After ruling out any other possible causes, your doctor will also refer your child to an allergy clinic so you can get a proper diagnosis of the allergy and a plan for making any necessary changes to your child’s diet.

Anaphylaxis This is a rare but severe type of allergic reaction that needs urgent treatment. Call 999 and ask for an ambulance immediately if you notice any of the following signs (either with or without the other allergy symptoms described above) in your baby:

  • Swollen tongue

  • Breathing difficulties

  • Trouble swallowing or speaking

  • Dizziness or fainting

  • Floppiness or collapsing.

Common Foods That Cause Allergic Reactions

Here’s a list of the foods that are most likely to trigger an allergy in your baby or toddler:

  • Cow's milk. Most children with a cow’s milk protein allergy outgrow it by the time they start school. Note that most baby formulas are made with cow's milk, so if you're formula-feeding and your infant is allergic to milk, your doctor may advise you to switch to a hypoallergenic formula. If you're breastfeeding and your infant has a milk allergy, you may have to follow a milk-free or dairy-free diet yourself too.

  • Eggs. Luckily, children usually grow out of food allergies triggered by eggs.

  • Peanuts. These are not actually nuts; rather, they are legumes similar to beans and peas. Most children do not outgrow their peanut allergy.

  • Tree nuts (almonds, cashews, hazelnuts, pecans, pistachios and walnuts). Having a nut allergy doesn’t automatically mean you’re also allergic to peanuts: It’s possible to be allergic to just tree nuts, just peanuts or both. Allergies aside, you should not give your child whole nuts or peanuts until at least 5 years of age, as they pose a risk of choking.

  • Soya. Children often grow out of a soya allergy by the age of 7 to 10 years old.

  • Wheat. A wheat allergy is different to a sensitivity to gluten (which is also found in rye and barley—not just in wheat). A wheat allergy can cause a serious allergic reaction, whereas a gluten sensitivity wouldn't. Most children outgrow a wheat allergy.

  • Fish. This food allergy usually lasts into adulthood.

  • Shellfish (shrimp, mussels, scallops, prawns, lobster, etc.). Children don’t usually grow out of this food allergy.

As you can see, there is a bright side to some of this: Many children outgrow food allergies, especially when it comes to eggs, milk, wheat and soya. Speak to your child’s doctor or your health visitor if you have any questions about your baby’s food allergy and what steps you can take to reduce the risks of exposing your baby or older child to the allergen.

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

Sometimes children aren't allergic to a certain food, but instead have an intolerance for it. Intolerance of certain foods (basically an inability to digest the food) is less serious than a food allergy (which can result in a very serious allergic reaction) but it can still be an uncomfortable problem. A common food intolerance is milk and dairy intolerance, when your baby’s digestive system has trouble processing lactose, which is the natural sugar found in milk and other dairy products. The symptoms of food intolerances can usually be controlled through dietary changes, but the precise treatment depends on how mild or severe the intolerance is. Some of the symptoms may be similar to those of an allergy – or some other common childhood illnesses – so it’s important to see your child’s doctor for a diagnosis. Food intolerance symptoms usually appear a few hours after eating the food. They can include:

  • Tummy ache

  • Wind

  • Diarrhoea.

Can You Prevent Food Allergies?

There is no sure-fire way of preventing allergies in your child, but experts believe that waiting too long before introducing certain potential allergens to your baby’s diet may increase the risk of becoming allergic to them. Peanut and egg allergies, for example, may be more likely to develop if your child doesn’t encounter them until after 6 to 12 months old. Still, as you start your baby on solid foods it’s important to introduce possible allergenic foods carefully – in very small amounts at first, and one at a time so you’ll know what’s caused any reaction that does occur. Talk to your health visitor if you’re unsure how to safely introduce new foods to your baby or toddler .

How Are Food Allergies Diagnosed?

If you suspect your baby has an allergy or food intolerance, it’s important to make an appointment with your child’s doctor.

It's not a good idea to try to make your own diagnosis, and experts warn strongly against using home testing kits that may be available in the shops.

Your doctor will ask questions about your child’s symptoms, their severity and exactly how and when they appeared. You may also be asked whether anyone else in your family has allergies.

Then, based on the answers your baby may be referred to an allergy clinic for one or more of the following allergy tests:

  • Skin prick test (scratch test). This involves placing a drop of the allergen in a drop of liquid on your baby's skin and scratching the skin to see if there is a reaction. If swelling, redness or itchiness appear on the tested area of skin, the test is positive. The skin prick test doesn’t usually hurt.

  • Blood test. This allergy test is sometime done instead of a prick test. The quantity of allergic antibodies is measured in a sample of your baby’s blood.

  • Food elimination diet. This involves removing the suspected food allergen from your baby's diet for two to six weeks, then reintroducing the food – under carefully controlled circumstances – to see if the symptoms disappear and then reappear again. This test should always be supervised by a specially qualified health professional, so don’t try doing it yourself without expert guidance or supervision.

What to Do If Your Baby Has Been Diagnosed With a Food Allergy

If your baby or toddler is diagnosed with a food allergy, it's best to begin avoiding that specific food immediately, even if the allergic reaction isn't a serious one. You'll need to be very mindful of what foods your baby or toddler is going to eat at all times, especially if it's food you didn't prepare. However, it’s important not to eliminate important food groups – such as dairy – from your child’s diet without discussing the changes with your doctor first.

Check Ingredient Labels

Be aware that many shop-bought foods contain traces of allergens, so you’ll need to start reading all product labels to make sure you aren't accidentally giving your baby or toddler something he or she may have an allergic reaction to. Unpackaged foods – like bakery or delicatessen-counter products – may not be labelled in the same way as pre-packaged food. Look for signs in the shop providing information about allergens or ask a member of staff. It's also a good idea to make sure your kitchen cupboards don't contain foods that contain traces of the allergen – you never know when your curious toddler may get hold of something he or she shouldn't be eating.

Precautions to Take With Serious Food Allergies

If your child has been diagnosed with a serious food allergy that can result in life-threatening anaphylaxis, the doctor will prescribe a special adrenaline auto-injector. Adrenaline is a life-saving hormone that narrows blood vessels to prevent a drop in blood pressure and opens up the airways to counter breathing difficulties. You’ll need to learn how to use the device so that you can inject it immediately in case your little one experiences an anaphylactic reaction. Read the manufacturer’s instructions carefully, especially the guidance on how to store and use the auto-injector. When your child is old enough, you should teach him or her how to self-administer an injection in an emergency. You’ll also need to make sure everyone who cares for your little one (including grandparents and babysitters, for example) knows how to use the injector, and you'll need to remember to replace the injectors when they expire. Caregivers, day care staff, nursery-school teachers, and friends and family members who care for your baby or toddler should all be aware of your child’s allergies and know what to do if an anaphylactic reaction occurs.

FREQUENTLY ASKED QUESTIONS

  • Symptoms of a food allergy can include:

    • Diarrhoea
    • Vomiting
    • Itchy skin or rash
    • A cough
    • Sore or itchy eyes
    • Runny nose
    • Swollen lips
    • Anaphylaxis (a rare but severe reaction that needs urgent treatment. Call an ambulance if your child has trouble breathing or swallowing, seems dazed or falls unconscious.).
  • The foods that babies and toddlers are most commonly allergic to include:

    • Cow's milk
    • Eggs
    • Tree nuts
    • Peanuts
    • Soya
    • Wheat
    • Fish
    • Shellfish.
  • If your baby is diagnosed with a food allergy your doctor may prescribe or recommend an antihistamine to relieve the symptoms. Severe allergic reactions or anaphylaxis may need to be treated urgently with adrenaline.
    Dietary changes will also be necessary to prevent symptoms from reoccurring.

  • Most babies with a milk, egg, soya or wheat allergy will grow out of it, often by the time they reach school age. Other allergies, for example a peanut allergy, are usually permanent.

The Bottom Line

If your baby or toddler is diagnosed with a food allergy, it may mean avoiding that food altogether, and making sure that everyone around him or her is knows exactly what to do if he or she has a severe allergic reaction. Luckily, many food allergies are outgrown by school age, and those that aren’t can be managed by being extra vigilant of what your little one eats or has access to. Like so many other aspects of parenting, this will probably soon become second nature – and you’ll be able to focus on the more enjoyable side of watching your little one grow and explore the world.

How we wrote this article
The information in this article is based on the expert advice found in trusted medical and government sources, such as the National Health Service (NHS). You can find a full list of sources used for this article below. The content on this page should not replace professional medical advice. Always consult medical professionals for full diagnosis and treatment.