Hayfever (allergic rhinitis)
Hayfever, or seasonal allergic rhinitis, is condition in which people experience an allergic reaction to different types of pollen during the year.
Hayfever is common in the UK, affecting around 1 in 5 people at some stage.
Tree pollen often triggers symptoms during the spring, grass pollen is in the air in late spring and summer and pollen from weeds is around from early spring into late autumn.
Hayfever can also be caused by mould spores, from late March until November, usually peaking in late summer and early autumn.
It is common for people to be allergic to more than one pollen.
A person who has perennial rather than seasonal rhinitis experiences allergy triggers all year round, from allergens such as house dust mites, mould, animal dander and feathers.
What are the symptoms of allergic rhinitis?
The body’s immune system interprets the allergen, such as pollen, mould or dander, as an invader and responds by releasing a chemical called histamine into the bloodstream.
Histamine causes inflammation ( swelling and redness) of the sinuses, nose and membranes of the eyes, and triggers sneezing. The swelling reaction is designed to block the allergen from entering the body and sneezing is a method to expel it out of the body. Histamine also allows extra fluids to enter the nasal tissue, resulting in congestion, itching and a runny nose.
People with allergic rhinitis have sudden sneezing, a watery nasal discharge, puffy eyes and fatigue.
Hayfever symptoms often start during childhood or teens, but can develop at any age.
How do I find out what causes my allergies?
The season in which your allergy occurs will narrow the list of possible culprits. To pinpoint the cause, your doctor may arrange for you to have a skin test to determine which substances or allergens cause a reaction.
The skin test involves placing extracts of potential allergens in a grid on your arm or back, and then pricking your skin so the extract can enter the outer layer of skin or epidermis. Those areas that become red and itchy indicate which substances trigger a defensive (allergic) response by your immune system.
Your doctor may recommend a blood test to check the levels of antibodies produced by the immune system. Elevated levels of certain antibodies can identify particular allergies.
Why do only some people get seasonal allergies/hayfever?
It is not known why some people get allergies while others do not. However, there is some evidence to suggest that hayfever and other types of allergies are hereditary (passed on from parents to children). People who suffer from asthma or eczema are also more likely to develop hayfever or perennial (year-round) allergic rhinitis.
Why are my allergies better on some days and worse on others?
While the pollen seasons for particular plants are very consistent within each geographical region, the weather plays a large role in determining how heavy the pollen count (and other potential allergens including mould) will be, both seasonally and daily. The severity of your allergic reaction will generally mirror the rise and fall of the specific allergen count to which you are allergic.