What Is A Food Allergy

What Is A Food Allergy

Many people get confused and say they have a food allergy when they actually an intolerance and more people understand allergies so sometimes it’s easier to say you have an allergy rather than to try and explain intolerances to people. Despite this, there is a big difference.


True allergies are those in which food causes the body to have a negative immune response. In other words, the body rejects the food eaten and thinks it is dangerous, like when you get a virus, your immune system kicks into gear and tries to destroy the virus. Allergies typically produce a fairly immediate response, or up to 4 hours after consumption of the irritant food.

The most severe form of food allergy is when anaphylaxis occurs. Anaphylaxis is when swelling causes the airway to close over and the person starts to suffocate.

Signs of anaphylaxis include:

  • swelling of the mouth
  • a pale face
  • an immense feeling of fear
  • difficulty breathing

This is a medical emergency and immediate lifesaving medical assistance is required. Every person with a food allergy has a different level of reaction to a particular food. Most people do not have such strong allergic reactions. Symptoms such as a rash, hives (red blister like swelling of the skin), eczema, vomiting, diarrhoea and/or tingling in the mouth are usually more likely to present.


People are usually born with food allergies. It is rare to develop an allergy as an adult. Often the first sign of an allergy is when a baby develops hives or eczema due to exposure to the allergen through breastmilk or formula. Later as they are weaned onto solid foods, the reaction becomes stronger. Food allergies can be diagnosed through skin prick testing (SPTs). Skin prick testing is conducted by an allergy specialist and involves minute amounts of the food being injected under the skin to test for a reaction. If there is a reaction, the skin will develop a welt. The size of the reaction is determined by the size of the welt that appears on the skin. Sometimes blood tests (RAST) tests are done, but SPTs are the most common.

A child under the age of one who has a negative response to a skin prick test, is not necessarily free from allergy. The response tends to get stronger after the age of one. However, a positive reaction, even in a child under the age of one, is a definite sign of an allergy.

Other diagnosis tests are available in the community but are not recognised as legitimate diagnosis tests. See The Australasian Society of Clinical Immunology and Allergy www.allergy.org.au for more information. Most people with true allergies are allergic to dairy, eggs, nuts, fish and soy. However, it is possible to be allergic to anything.


At Allergy Train, we aim to be a source of nutritional and food hypersensitivity information to guide you in your journey through an elimination diet or in learning to live on a restricted diet. However, the information provided on our site is for educational purposes only and should never be used to diagnose food hypersensitivity or other medical conditions. It is very important you talk to a health professional such as a doctor and a dietitian before you undertake any kind of dietary elimination process or restricted diet.


Our Allergy Train Pty Ltd website contains links to other websites to assist you with obtaining more information. However, we do not necessarily endorse all the content on these sites. Please critique each of these sites yourself before taking on board any of the information found on these sites.

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  • Jenny Trezise
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