Nut Allergy

Nut allergy has increased over the last few decades, particularly in countries such as Australia, and although reactions can be  mild it is the most common cause of food induced anaphylaxis. So far there is no cure and the only treatment is avoidance. Unlike other food allergies most nut allergies are lifelong. Peanuts are strictly a vegetable and are unrelated to tree nuts – which include cashews, hazelnut, walnuts, pecan, almond brazil, sesame.

What Reactions occur ?


localised lip swelling and rash

When coming into contact with nut the most common abnormal reaction is a dermatitis that develops within a few minutes – particularly around the mouth. There can also be more extensive skin reactions such as hives.

Anaphylaxis is the term used to describe serious life threatening allergy. By definition this means that the respiratory system and cardiovascular system are involved. In a child this will involve narrowing of the airways leading to noisy troubled breathing, wheezing and shortness of breath. This is associated with a drop in blood pressure and collapse. By this time adrenaline must be given without delay.

When does allergy start ?

Nut allergy can occur at any age but may is often noticed during infancy or early toddler years. These early reactions usually involve contact with peanut butter. The infant will appear distressed, spit out the food, and there will be an accompanying rash around the mouth, some lip swelling, maybe coughing. Parents will recognise this as a reaction and

How does allergy occur ? sometimes call an ambulance. If possible a photograph or video is invaluable to confirm the diagnosis.  Anaphylaxis to nuts tends to occur in older children. It is very rare for infants to have serious reactions. In this age group the reactions are usually isolated to the skin and area around the mouth.

For some reasons that are not entirely clear the presence of the nut protein triggers a reaction in the immune system that makes the body think it is under attack. The offending protein links up to an antibody called IgE. The IgE reacts with cells under the skin and in the body which release  chemicals that cause the allergy symptoms. Allergic reactions are somewhat like avalanches. There is a self perpetuating cascade of chemicals released from these tiny cells, and if they get out of control the massive outpouring of chemicals causes problems with breathing and the cardiovascular system as in anaphylaxis. Unfortunately there is sometimes no clear picture where the avalanche will stop.

Diagnosing using Skin Prick testing

One of the most accurate ways of detecting allergy is through skin prick testing. The forearm has a drop of protein extract impregnated just under the skin and if there is the development of a small insect bite like mark then this suggests allergy to nut. If there is no reaction at all then it can be assumed there is no risk of IgE reactions. This is usually done along with other food proteins such as egg, soy, cows milk. These tests are generally safe and accurate and if done properly using appropriate distraction techniques are well tolerated by infants toddlers, and children.  For nut allergy they should be repeated every couple of years.


Once diagnosed avoidance of food that contains the offending nut or nuts is the only treatment. This means careful shopping and ensuring that schools, and close family are educated in avoiding foods and treatment of anaphylaxis. It is hard to get the balance right sometimes where the child should not feel like he or she feels ‘cocooned’ but on the other hand ensuring that all situations are prepared for just in case. I tend to use the term ‘sensibly paranoid’.


Anaphylaxis is a term used to describe the life threatening allergic reactions that can occur. The increased incidence of food allergies have resulted in Anaphylaxis guidelines and support material. These are found at

derived from Greek ana=against phylaxis=protectionHere are some additional points about anaphylaxis.

  • The chances of dieing from anaphylaxis are miniscule. There is one death every 2 years from food allergies despite thousands of anaphylactic reactions occurring during this period
  • The current policies to have peanut free childcares and schools is not a guarantee that peanuts are not present. Because of the range of foods that can contain peanuts it is currently not practical to be sure peanut traces absent.
  • Anaphylaxis can be treated very successfully using the adrenaline pen called epipen. They are safe, pose virtually no danger, and should be used as per the guidelines.
  • Anaphylaxis from foods – even peanuts – is exceptionally rare in infants and small children. Generally this is an older child and adolescent/adult problem.


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