Allergic reactions in babies

baby allergic reaction

For many parents, the first sign that a baby has an allergy comes when he begins to wean onto solid foods, but some children may react earlier to environmental causes or even to traces of foods in your breastmilk. An allergic reaction can be far more serious than an intolerance so it's vital to know how to spot the signs of an allergy and what the causes might be.

What is an allergic reaction?

An allergic reaction occurs when the immune system perceives a food or substance as a threat to the body. For most people, these triggers are harmless but babies with a sensitivity can develop a physical reaction in the form of a rash, illness or severe shock. Babies who already suffer from eczema tend to be prone to food allergies.

Research estimates that around 40% of children in the UK will suffer from an allergy at some point. Fortunately, most will grow out of it by the time they go to school.

What does an allergic reaction look like?

If your child has an allergic reaction they may show one or more of the following symptoms:

  • Cold-like symptoms including a runny nose, sore throat and a cough
  • A red, itchy rash
  • Upset tummy, including vomiting or diarrhoea
  • Difficulty breathing, including shortness of breath or tightness in the chest
  • Itchy, red eyes or conjunctivitis
  • Swollen eyes or lips

What is anaphylactic shock?

In very severe cases, a baby's immune system can overreact to a trigger and result in anaphylaxis. Anaphylactic shock is rare but can come on suddenly and is highly dangerous if not treated quickly. It usually starts like any allergic reaction with a rash or runny nose but progresses rapidly with symptoms including:

  • Breathing trouble and tightness in the chest
  • Swollen lips or tongue
  • Dizziness or confusion
  • Rapid heartbeat
  • Paleness and clammy skin
  • Fainting or losing consciousness

If your child has symptoms of anaphylactic shock, you should call 999 immediately and remove the substance that has triggered the reaction. If your little one has suffered anaphylaxis before then you may have an auto-injector that you can use. These injectors contain adrenaline – the main antidote for anaphylaxis. The most common type of auto-injector is an EpiPen.

Testing for food allergies

If your baby has allergies and you are beginning the process of having them diagnosed, it's useful knowing what the testing procedure involves. Watch our video below to find out.

Common food allergies in babies

If your baby is allergic to a food, he'll likely show signs of it in his first year. Certain food allergies are particularly common in children. These include:

Cow's milk allergy and lactose intolerance

The UK has the highest incidence of cow's milk allergy in Europe, affecting about 5% of children under the age of three. If your baby has an allergy to cow's milk then it may appear when you are breastfeeding as traces of certain foods can pass to your baby through your milk. Cow's milk allergy in babies can produce symptoms that include:

  • colic
  • restless sleep
  • vomiting or reflux
  • diarrhoea or constipation
  • wheezing
  • cold-like symptoms, including runny nose
  • eczema
allergic reaction

Some parents confuse cow's milk allergy with lactose intolerance. If your baby has an allergic reaction to cow's milk, it's because his body treats the protein in cow's milk as harmful. On the other hand, if he is lactose intolerant, it's because his body doesn’t make enough of the lactose enzyme that breaks down the lactose sugar in cow's milk.

Lactose intolerance is very rare in young babies and tends to develop at an older age. The sensitivity is more common in children of Asian, African and Hispanic descent. If a baby is lactose intolerant from birth, then even breastmilk can cause a reaction. Symptoms include diarrhoea, vomiting, gas and belly pain. However, if your baby is showing typical allergy signs, such as wheezing or a runny nose, then it's more likely that he's allergic to cow's milk rather than being lactose intolerant.

If you are concerned that your baby has either sensitivity, you should see your GP. A cow's milk allergy is diagnosed through a blood test and, if confirmed, you'll need to eliminate the milk from his diet along with any products that contain it. If you're breastfeeding you'll need to eliminate them from your diet temporarily, too. Lactose intolerance can be diagnosed in a number of ways including a breath test. If your baby is diagnosed with it, your doctor will recommend lactose-free formula or lactose-free foods.

Our youngest son had a cow’s milk allergy. Once all dairy was cut out he was fine and he grew out of it by the age of two. There are lots of great recipes and advice online. Some of the dairy-free formula sites can also offer good recipes.

Other common food allergies in babies

  • Eggs. An allergy to eggs produces symptoms that include hives, eczema, upset stomach and runny nose. Your baby may be allergic to eggs in their entirety or he may just be allergic to the yolk or white, or a reaction may be caused by eggs that are not completely cooked through. Around 1% of children will suffer from an egg allergy but most will grow out of it by the age of five. Your baby will need to avoid eggs until then and you'll need to look out for 'hidden eggs' that are ingredients in other foods such as cakes and fresh pasta.
  • Wheat. If your baby is allergic to wheat, a reaction will be triggered by one of the four proteins found in the grain or by all of them. He'll show typical allergy symptoms but in severe cases, a wheat allergy can trigger anaphylaxis. Wheat allergy is more common in babies and toddlers than in adults as most infants outgrow it.
  • Gluten. Be careful not to confuse a wheat allergy with gluten intolerance, also called coeliac disease. Gluten is a protein found in other grains besides wheat, including barley, rye and oats. If your baby has coeliac disease, then it will affect his small intestine and symptoms will tend to be related to digestion, with an upset stomach being the primary sign.
  • Nuts. Up to 2% of children will develop a nut allergy by the time they are two. Symptoms include a hive-like rash around his mouth which tends to spread, along with a swollen tongue or lips. Unless you know that your child has a nut allergy there is no reason to stop eating nuts while pregnant or breastfeeding. You should avoid giving your child nuts or nut products until he is at least six months. Nut allergies have the potential to be fatal. If you suspect that your child has an allergy to nuts, you should speak to your doctor.
  • Fish and shellfish. This type of allergy produces typical symptoms but can lead to anaphylaxis and your child will usually need an auto-injector like an Epi-pen. Be careful of cross-contamination when preparing other foods.
It can all be very overwhelming when your child is first diagnosed with a food allergy but you do get used to it all. My first supermarket shop after my daughter’s nut allergy diagnosis took me hours but you learn to be a packet-reading expert over time.

Other common allergies in babies

Aside from food sensitivities, children can also be allergic to common substances in their environment. Environmental allergies include:

  • Hay fever. This is the name given to the symptoms associated with an allergic reaction to pollen. Symptoms include sneezing, itchy eyes and a runny nose. Hay fever tends to affect babies and adults between May and October. The bad news is that most hay fever medicines are not suitable for babies so you'll need to take steps to limit your baby's exposure on high pollen days. Keep an eye on the forecast so you know when these days are. Use a cold, wet flannel to wipe down your baby's face and use a wide-brimmed hat to protect his eyes and nose. You could also try wiping some balm or petroleum jelly under his nose to act as a barrier.
  • Dust mites. Your baby will usually produce symptoms similar to hay fever but a dust mite allergy can lead to asthma attacks. It's impossible to completely eliminate dust from your home but you can take steps to limit it. Clean and hoover at least once a week and wash your baby's bed linen on a hot temperature weekly. Keep your home well ventilated and, if possible, remove carpets, as this is where dust mites love to live.
  • Pets. If your baby is allergic to your dog or cat, then it's likely to be caused by the animal's dander or skin flakes. Symptoms will be similar to hay fever but will last all year round.
  • Anaesthetic, medicines or dyes found in certain medicines can produce an allergic reaction.
  • Fragrances. Your baby might react to strongly fragranced lotions or moisturisers and you may need to switch to one for sensitive skin or find a natural alternative.
  • Bee stings or insect bites. Most children will react in some way to a sting or bite usually in the form of localised swelling. If your baby has been stung multiple times or he has an allergy to the bee or insect venom, then it may result in anaphylaxis and you should call 999.
  • Latex. Some children are allergic to the protein in latex that makes it rubbery. Reactions can vary from a mild, itchy rash through to anaphylaxis. Latex allergies are rare and tend to only occur in babies that have had excessive exposure to the product. So if your baby has been poorly and been operated on at a young age, his chances of developing an allergy are higher. There is no cure for a latex allergy so you'll need to exercise caution around things like rubber balloons, certain toys and your baby's dummy.
  • Mould. Your baby can develop an allergy to mould if he's had excessive exposure to it, such as sleeping in a damp room. Certain foods, such as cheese and mushrooms, which contain mould spores, can trigger a reaction, too.

How are allergies diagnosed?

If you suspect that your baby has an allergy, speak to your doctor. Certain allergies may have specific tests but most are diagnosed with either a blood test or a skin-prick test.

A skin-prick test is the preferred method of testing for young babies as it's painless to carry out. Your doctor will place a small amount of liquid containing the suspected allergen onto your baby's skin. Then the skin beneath the liquid is pricked with a needle. If a red, itchy bump appears within 15 minutes, your doctor will be able to confirm the allergy.

If your baby is also showing signs of eczema alongside an allergy, then your doctor may also carry out a patch test where the allergen is applied to the skin and your baby's reaction is monitored over 48 hours. These methods of testing might be carried out alongside an elimination diet where you'll be asked to remove certain foods, reintroduce them and monitor your baby's reaction.

If your baby is diagnosed with an allergy, your doctor will advise you on the best course of treatment. In nearly all cases, this involves avoiding the food or substance which causes the allergy.