Food allergy
A food allergy is an immune system response, almost always to a food protein, that the body mistakenly believes is harmful. The foods that cause allergic reactions are known as food allergens. When a person eats food containing the allergen, this can lead to signs and symptoms of an allergic reaction. Food allergies can be either IgE-mediated or non-IgE-mediated.
Non-IgE-mediated food allergy
Non-IgE-mediated food allergy is often referred to as gastrointestinal (gut) food allergy. For this reason, it is sometimes confused with food intolerance. Reactions happen because of an abnormal immune response to food proteins and are generally delayed (1 to 72 hours after eating or drinking the food). These allergies do not cause anaphylaxis.
IgE-mediated food allergy
An IgE-mediated allergic reaction can occur after eating a small amount of the food allergen and can involve the gut, skin and breathing and/or heart systems. Symptoms of food allergy can be mild to moderate or severe (known as anaphylaxis).
There is no cure for these food allergies, strict avoidance of allergens is required. However there are new treatments such as oral immunotherapy (OIT) that can increase the amount of a food a person can eat before they have an allergic reaction. This must be done under the medical supervision of an allergy specialist as there are strict guidelines and some people can experience anaphylaxis during the treatment.
Food intolerance
A food intolerance is an adverse reaction to a food. Food intolerances, such as lactose intolerance, are dependent on the amount of food eaten, meaning people with a food intolerance can usually eat small amounts of the trigger food without symptoms.
A food intolerance can cause gastrointestinal (gut) symptoms such as bloating, gas/flatulence, diarrhoea, constipation, stomach pain as well as headaches, migraines and fatigue.
Lactose intolerance
Lactose intolerance is not an allergy and does not cause life-threating allergic reactions. People with lactose intolerance can experience symptoms such as diarrhoea, nausea, stomach cramps and bloating when they have dairy products with lactose because they cannot digest the lactose.
People with lactose intolerance do not need to completely avoid all dairy products. They may need to limit their intake or choose lactose-free products. It is important that they talk to their doctor or dietitian for advice.
Lactose-free products still contain milk protein and MUST NOT be given to people with a milk allergy.
For more information, visit ASCIA Lactose Intolerance.
Coeliac disease
Coeliac Disease is not a food allergy or food intolerance, but does involve the immune system. People with coeliac disease must avoid all food containing gluten. Gluten containing cereals, such as wheat, barley, rye and oats (in some people) can cause inflammation leading to symptoms such as diarrhoea, stomach pains, bloating and fatigue. The symptoms are not immediately life-threatening but can cause long-term health and nutrition problems.
For more information, visit Coeliac Australia website.
Delayed non-IgE-mediated food allergy
Non-IgE-mediated food allergy is often referred to as gastrointestinal (gut) food allergy. For this reason, it is sometimes confused with food intolerance. Reactions happen because of an abnormal immune response to food proteins and are generally delayed (1 to 72 hours after eating or drinking the food).
A non-IgE-mediated food allergy cannot be diagnosed with a skin prick test or IgE antibody blood test. A diagnosis can only be made after an elimination diet.
For more information, visit our Non-IgE-mediated food allergy webpage.
Further information
For further information on food intolerance visit ASCIA Food Intolerance.
Food Allergy
Learn more about how food allergies work and tips and guidance for living with a food allergy.