Hay fever (sometimes called allergic rhinitis) is a
common allergic reaction to pollen, which is why symptoms usually appear when the
pollen count (the number of grains of pollen in one cubic metre of air) exceeds 50.
1,3 This usually occurs on sunny, windy or humid days.
2
When pollen comes into contact with the mouth, nose, eyes and throat of someone with the allergy, the cells in the nasal passage become sensitised – that is, they start reacting to the pollen.2,4
These sensitised cells then trigger the production of antibodies (proteins that try to protect you from unwanted substances entering the body), which leads to
the release of histamine.
4,6 It’s this histamine that triggers the onset of hay fever symptoms.
4,5
For people who are allergic to pollen, it can cause significant irritation and inflammation, leading to a blocked nose and symptoms like sneezing.1 However, not everyone reacts to pollen in this way.
For most people, exposure to this powdery substance is completely harmless and causes no reaction whatsoever.1
But, depending on your genetics, you may be more likely to experience hay fever symptoms.3 If, for instance, you have a family history of allergies, or have asthma or eczema, the likelihood of you having hay fever may increase.1,6,7