Food allergies in babies

What is a food allergy?

A food allergy is when your baby’s immune system has a bad (adverse) reaction to a usually harmless protein in a food, and tries to fight it by producing antibodies.

If your baby has a food allergy, he’s likely to show symptoms just a few minutes after having the food.

How common are food allergies in babies?

Food allergies are common in babies and young children. About 10 per cent of infants, and between four and eight per cent of children up to five years old, have a food allergy (ASCIA 2015a).

Your baby is more likely to have a food allergy if you have a family history of allergies, such as asthma, hayfever, food allergy or eczema (Lack et al 2003, NICE 2011). The link between food allergies and eczema is the strongest.

Babies who have severe eczema when they’re young are more likely to have a food allergy (Allergy UK 2013, Cummings et al 2010). Generally speaking, the earlier eczema starts, and the more severe it is, the more likely your child is to develop a food allergy (NHS 2014).

Which foods cause the most allergies?

The most common food allergies in babies and young children are eggs, cow’s milk, peanuts and tree nuts (such as pine nuts, cashews, macadamias and pecans) (ASCIA 2015a). The statistics are:

• milk: about one in 50 Australian babies have a cow’s milk allergy (ASCIA 2010b)
• eggs: about eight per cent of babies are allergic to eggs, though for the majority it resolves as they get older (Osborne et al 2011)
• peanuts: about three per cent of children are allergic to peanuts (ASCIA 2014a)

Seafood, sesame, soy and wheat can also cause allergies (ASCIA 2015a).

What symptoms should I look out for?

It’s easy to tell if your baby has an immediate allergy to a food. The signs and symptoms include:

• hives (welts) around his mouth, nose and eyes, which can spread across his body
• mild swelling of his lips, eyes and face
• runny or blocked nose, sneezing and watery eyes
• itchy mouth and irritated throat
• nausea, vomiting and diarrhoea
  (NICE 2011)

If your child has a more severe reaction, he may be wheezing, have breathing difficulties, throat and tongue swelling, and a sudden drop in blood pressure. This is known as anaphylaxis, or anaphylactic shock, and can be life-threatening.

Fortunately, severe reactions are rare (ASCIA 2015b). If you suspect your baby is having a severe allergic reaction, use an adrenaline auto-injector pen if he’s been prescribed one, and call an ambulance immediately. Don’t try to make him vomit (ASCIA 2015c).

What happens if my child’s food allergy isn’t immediate?

Delayed allergic reactions are harder to spot, but are becoming more common. Your baby’s body will take longer to react, because different parts of his immune system are affected. These allergies are called delayed-onset, or non-IgE-mediated allergies.

Signs and symptoms to look out for include:

• reflux
• colic
• diarrhoea
• constipation
• blood or mucus in your child’s poo
• moderate to severe eczema, which is common in babies with a milk allergy
  (NICE 2011)

All these symptoms are common in early childhood, though. An allergy is only one possible explanation (NICE 2011).

How is a child’s food allergy diagnosed?

If you think your baby is allergic to a food, see your GP and ask for a referral to an allergy specialist or a hospital with an allergy clinic, if you have one nearby.

After taking a full history of your baby’s symptoms, your doctor will probably suggest a skin prick test to help with the diagnosis. This is particularly useful when diagnosing small babies. Your doctor may also do blood tests and the results combined (NICE 2011, 2012).

Don't be tempted to buy commercial testing kits, which are sold online, by mail order or in health food shops. There is little evidence that these work.

If your child is having a delayed allergic reaction to a food, your doctor will try to track the allergen down by a process of elimination. You’ll be referred to a dietitian, who will explain how to cut out various foods from your child's meals. Suspected foods will probably need to be avoided for between two and six weeks. Don’t cut out foods from your child’s diet without talking to your doctor or a dietitian first.

If your baby has a milk allergy and you’re breastfeeding, your doctor or dietitian will advise you about changing your diet. If you’re formula feeding, you may be advised to change to a hypoallergenic formula milk (NICE 2011).

The dietitian will review your child's symptoms and slowly reintroduce the suspected allergen to his diet to see if the symptoms return. She may do another skin-prick test before reintroducing the food.

Can I prevent my baby from developing a food allergy?

Don't worry about what you eat during your pregnancy or while you’re breastfeeding. There’s no evidence that it will affect your baby's chances of developing an allergy (ASCIA 2010a, Kramer and Kakuma 2012, NHS 2015, NICE 2011). So, for example, unless you’re allergic to peanuts yourself, it’s safe to eat peanuts during pregnancy and while breastfeeding.

Breastfeeding exclusively for at least four to six months may help reduce your baby’s risk of developing allergies (Snijdres et al 2007, Thyagarajan and Burks 2008), though the evidence is mixed (Matheson et al 2012).

If you’re formula feeding your baby and you have a family history of allergies or eczema, there’s no strong evidence that partially or exclusively hydrolysed formulas reduce the risk of him developing an allergy (ASCIA 2016). These formulas are usually labelled “HA” or “hypoallergenic”. They’ve been processed to break down some or most of the proteins that trigger reactions in children with mild to moderate allergy to cow's milk. Soy milk and other non-cow milks, such as goat milk, aren’t recommended for preventing allergies either (ASCIA 2016).

There’s no evidence to suggest that delaying the introduction of foods that often cause allergies will help to prevent allergies. Rather, recent evidence suggests that the earlier your baby eats or drinks a potential allergen, the less likely he is to develop an allergy to it (ASCIA 2010). When you start feeding your baby solids, introduce a new food every couple of days (ASCIA 2010a). That way you’ll be able to tell if one of them causes a reaction.

There’s some evidence that babies can be sensitised to peanuts through their skin (ASCIA and AAA 2015, Fox et al 2009, Lack et al 2003, Strid et al 2005). So if you have a family history of allergies, or if your baby has eczema, avoid using any skin care products on him that contain peanut oil (also called arachis oil), or touching him after handling peanuts or peanut butter.

Taking probiotics either as a supplement while you’re breastfeeding, or added to your baby’s formula milk, may help to reduce the risk of him developing food allergies, but we need more evidence to be sure (ASCIA 2015b, Osborn and Sinn 2007).

Can food allergies be cured?

There are no cures for food allergies yet, although progress is being made in understanding how to prevent and treat them.

Your baby may grow out of his allergy, but it may depend on what he's allergic to. Up to 90 per cent of children outgrow cow's milk and egg allergies, for example, whereas only about 10 to 20 per cent outgrow peanut allergies (Burke 2008). Your child will need to see a doctor regularly and be retested at intervals to see if he’s outgrown his allergy (Allergy UK 2013).

Even if he outgrows his allergies, he may still go on to develop other allergy-related, or atopic, conditions, such as asthma or hayfever. This is known as the allergic or atopic march.

What’s a food intolerance?

Delayed allergies and intolerances are easily confused. Babies can sometimes develop an intolerance to certain foods. This is different to an allergy because it doesn't involve the immune system (ASCIA 2015a). Your baby has an intolerance if he has difficulty digesting certain food. He might have:

• tummy pain
• colic
• bloating
• wind
• diarrhoea
• vomiting

The most common intolerance in babies is milk or lactose intolerance. This usually happens after a tummy upset and can last for a few weeks.

Some babies react to strawberries, but this is usually because of an intolerance rather than an allergy. They react to the natural acids and salicylates in the strawberries, but most babies will outgrow their intolerance. Other fruits containing these chemicals, such as citrus fruits and tomato, can also cause these reactions in babies.

If you suspect that your baby has a food intolerance, see your GP. Never try to diagnose it yourself, as there are other conditions that can cause similar symptoms, such as coeliac disease, when the gut reacts to the gluten in grains (Bingley et al 2004).

The food that troubles your baby is identified in much the same way as an allergen that causes a delayed reaction. Your doctor will refer him to a dietitian, who will put him on an exclusion diet, where suspect foods are removed from his meals and then slowly reintroduced. This helps to identify which foods are causing the problem.

How should we manage a food allergy?

Once your baby’s food allergy has been diagnosed, always follow your doctor's or dietitian's advice about avoiding trigger foods. If your baby has a mild allergy, for example to eggs, he may still be able to eat foods that contain baked eggs. But if he has a severe allergy, for example to nuts, he may need to avoid all traces of them.

You’ll need to plan holidays, food shopping, birthday parties, eating out and days out more carefully. But providing the right food and drink for your child, and advising others about how they can, too, will soon become second nature.

Take your child's medication with you whenever you go out. This may be antihistamine medicine, prednisolone or, if your baby is at risk of a severe reaction (anaphylaxis), an adrenaline auto-injector pen (Epipen) as well.

How do I shop for a special diet?

Shopping for a special diet can be a challenge at first. Your doctor or dietitian will help you understand food labels and manage “may contain traces” advice.

Reading food labels will become a part of everyday life. There are now special "free-from" ranges in most supermarkets, and many stores provide lists of own-brand foods that are free from nuts, eggs and milk.

If your baby is allergic to eggs, be wary of baked foods and cake decorations. These are often glazed with an egg wash to make them shiny, or so that sugar will stick to them.

You’ll need to check labels on non-food products, too, such as shampoos, cosmetics and moisturisers. Food ingredients, such as nut oils, are sometimes used in these.

Once you get to know all the products that are suitable for your baby you’ll be able to ensure his diet is varied, nutritious and tasty, without exposing him to his trigger food.

Where can I find out more?

• The Australasian Society of Clinical Immunology and Allergy website has a lot of referenced articles on allergies and infant feeding guidelines.
• Allergies and Anaphylaxis Australia is a charity that provides support and a lot of useful information about living with food allergies, including allergen cards (to help you identify which foods may contain allergens) and food alerts (that may affect people with food allergies).
• The Allergy-free Cookbook by Alice Sherwood, published by Dorling Kindersley, and Allergy-free Cooking for Kids by The Australian Women's Weekly are useful sources of recipes.

Find out more about milk allergy and intolerance and test your knowledge with our food allergy quiz.