How your body reacts

Rollover the first aid icons on the figure to find out more about how your body reacts to allergens.

Then scroll down the page to view videos on: 

1. the allergic reaction
2. sensitisation 
3. anaphylaxis

How the allergic reaction happens

Food allergy is a two-step process: initial symptom-free sensitisation to the allergen followed by an allergic reaction on the second and subsequent exposures.

Sensitisation is the recognition by the body of a particular substance – such as a food protein – as harmful. However, the person does not experience any symptoms at this stage.  We still don’t know why sensitisation to certain substances happens in the first place. There is evidence that sensitisation to an allergen can occur via a number of routes: via the digestive system after eating, via the respiratory system after breathing, through broken skin; and in the womb, through the mother’s diet.

At the biochemical level, the response to a food allergen is similar to that caused by other allergens such as pollen, pet hair, insect stings or house dust mites.

A good general introduction to the allergic process can be accessed in the following video:

The process of sensitisation followed by allergic reaction on the second exposure is described in more detail in this video:

The progression to an anaphylactic reaction is described in this video: