Introducing allergens

Note: If you are concerned about the risk of allergy in the family please consult a specialist before introducing any allergens and if there is a reaction to any foods please ensure you seek medical attention immediately.   If there are symptoms of anaphylaxis (difficult/noisy breathing, pale and floppy, swollen tounge) call an ambulance immediately.

A food allergy is an abnormal response of a person’s immune system to a food allergen, which is always a protein.  The immune system recognises the food allergen as ‘foreign’ or dangerous and reacts with subsequent effects in one or more areas of the body.  The reaction to the allergen is reproducible (that is, it will occur each time the person is exposed to the allergen).

Introducing allergens can be a confusing and worrying time for all parents.  And to add to the worry there is a lot of conflicting advise on this topic.  Until recently both the national and international recommendations where to delay some common food allergens however recent research has shown that there is no convincing evidence to support delaying the introduction of highly allergen foods.

For all babies new foods should be introduced one at a time to allow the detection of reactions to individual food components .

Signs and symptoms of an allergic reaction

Common sigs and symptoms of an allergic reaction are:

  • respiratory effects: nasal congestion and a runny nose, sneezing, asthma, coughing or wheezing
  • skin effects: swelling of the lips, mouth, tongue, face and/or throat; itching; redness or rashes (for example, hives or eczema) or allergic conjunctivitis
  • gastrointestinal effects: intestinal cramps, diarrhoea, nausea, vomiting or colic
  • cardiovascular effects: tachycardia, hypotension, feeling faint, dizziness, or collapse.

Symptoms can be mild to very serve for all allergens. Anaphylactic shock or anaphylaxis is life threatening.  It is a ‘rapidly evolving, generalised multi-system allergic reaction characterized by one or more symptoms or signs of respiratory and/or cardiovascular involvement of other systems such as the skin and/or gastrointestinal tract.  Common triggers include food, stinging insects and medication.

Around 160 foods have been reported as causing food allergies but only eight of these are responsible for 90% of all allergic reactions to food.  Please note while the recommendations are that introducing’s allergenic foods early, the below notes and information on how to introduce these foods are for families with no history of allergy’s. If you have a history of allergies please consult your general practitioner or allergy specialist first.


Cow’s milk: cows milk is one of the most common causes of food allergy in infants. Most children eventually outgrow their allergy and although symptoms can persist into adulthood, it is rare.  Milk allergy occurs when the immune system reacts to the protein in milk. If your child is diagnosed with a milk allergy, you need to completely eliminate milk, dairy products and any foods with milk-containing ingredients from their diet.

For those with no family histroy of allergy introduce dairy products around 7-8months. Cultured products such as yoghurt (high fat, natural), cheese or milk (standard/blue top) and butter in cooking are gentle on little tummies.  While it is recommened for dairy to be introduced before 12 months old, for babies under 12months old it is important that breast milk or formula is still their main source of milk as cows milks contains higher levels of protein and salt than are safe for babies immature kidneys. It also does not provide the vitamins and minerals a growing baby needs, especially iron.

Babies who are intolerant to milk will have symptoms of bloating, gas, or loose stools. Intolerance is caused by an inability to digest lactose into simple sugar.


Eggs:  Egg allergy is the second most common food allergy after cow’s milk allergy (5).  Previously it was recommended that egg yolk was introduced first as the egg white in particular contains the protein known to cause allergic reactions.   However due to recent research now the recommendation is to introduce cooked egg whole from around 6 months as new evidence on allergenic foods indicate that early introduction can reduce the incidence of allergy (6). Runny eggs are to be avoided and best practise is for a well-cooked egg.  Eggs can be mashed in with vegetable purees such as kumara or avocado and when baby is ready for more texture or finger food scrambled eggs and baked eggs are great options.  Eggs are a great early food as it’s a complete protein and they contain healthy fats. However it is common for babies to dislike eggs on their first taste due to the texture so please do not worry if this happens, it just means they may need a few more oppurtunities and tastes (up to 21!) to like them.  Trying a different cooking method or styles can be a great start.

If an egg allergy is present, both egg white and the egg yolk will need to be avoided.

Peanuts:  Parents are often worried about introducing peanuts as reactions can be the most immediate and life-threatening allergy.  And peanut allergies are not often grown out of. The 2015 Learning Early About Peanut Allergy (LEAP) was the first gold-standard study, which looked at preventing food allergy in high-risk infants. It was based on a hypothesis that regular eating of peanut-containing products, when started during infancy, will form a protective immune response instead of an allergic immune reaction.  The study showed that in high-risk infants, sustained consumption of peanut beginning in the first 11 months of life was highly effective in preventing the development of peanut allergy.  A natural smooth peanut butter (no added sugar or salt) is an easy way to introduce peanuts in isolation, off your finger. Its is not recommended to smear or rub food on your baby’s skin, especially if they have eczema as this will not help to identify possible food allergies.  However you can rub a small amount of the food inside your baby’s lip as a starting point.  If there is no allergic reaction after a few minutes, you can start giving small amounts of the food.

Tree nuts:  Almonds, brazil nuts, cashews, chestnuts, hazelnuts, hickory nuts, macadamia nuts, pecans, pinenuts, pistachios, and walnuts are tree nuts.  Another common allergy.  These can be introduced after 6 months like peanuts, remember its best to still introduce them individually and never give children whole nuts before they are at least 5 years old.  Nut butters (no added sugar, no or low added salt) or ground are ways to introduce. Remember nut butters are thick pastes and are classed as a choking hazard so if need be add water to make a thin paste.

Soy: Soy can be a confusing food item as while it is a top allergen there is also infant formula made from you! Soy is from soybeans and is a traditional food for many cultures.  It is considered to be a source of protein, iron and calcium. Tofu and edamame are foods that can be offered once baby is eating a variety of foods as it is not recommended for a first food.  As with any allergic reaction, a soy allergy occurs when the body mistakes soy as a harmful invader.

Fish & Shellfish:  A fish allergy is not exactly the same as a seafood allergy.  Fish can be introduced from 6 months with both white fish, oily fish (salmon).    Fish is a great source of protein and omega 3. Fish can be pureed with vegetables or cooked into soft pieces as finger foods.  Ensure the fish is entirely de-boned.

Wheat: Wheat is a common allergen which often resolves in early childhood.  An allergy to wheat involves an allergic response to a protein in wheat with gluten being one of the wheat proteins that can cause an reaction. Gluten is also involved in a condition called celiac disease which is an autoimmune disorder and different to a wheat allergy.  Celiac disease is a response in the intestines and affects the absorption of food and nutrients.  Introduce wheat from 8-10months of age, choosing wholegrain varietys.  Be aware of whole seeds as these can be a choking hazard.



Ministry of Health Food and Nutrition Guidelines for Healthy Infants and Toddlers aged 0-2 years 

Prescott S, Tang M, Bjorksen B.  2007.  Primary Allergy Prevention in Children: updated summary of a position statement of the Australian Society of Clinical Immunology and Allergy. MJA Practice Essentials: 54-58

ESPGHAN (European Society for Peadiatric Gastroenterology Hepatology and Nutrition Committee for Nutrition). 2003. Complementary feeding: a commentary by the ESPHGAN Committee on Nutrition.  Journal of Paediatric Gastroenterology and Nutrition42: 99-110

ASCIA (Australasian Society of Clinical Immunology and Allergy). 2007. Anaphylaxishttp:/

Zeiger RS. 2003. Food allergen avoidance in the prevention of food allergy infants and children. Pediatrics111:1662-71

Caubet JC, Wang J.  2011.  Current understanding of egg allergy.  Paediatric Clinical North America. 58(2): 427-43

Tan et al. 2017. A randomized trial of egg introduction from 4 months of age in infants at risk for egg allergy. Journal of Allergy and Clinical Immunology. 139, (5), 1621-1628.e8

Wood RA. 2003. The natural history of food allergy. Paediatrics111:1631-7

Du Toit G, Roberts G, Sayre PH, Bahnson HT, et al. 2015. Randomized trail of peanut   consumption in infants at risk of peanut allergy.  New England Journal of Medicine372(9), 803-813.