Hayfever is an allergic reaction to pollen. When pollen comes into contact with the cells that line your mouth, nose, eyes and throat, it irritates them. If you are allergic to pollen, your body thinks it is harmful and produces a special type of antibody known as immunoglobulin E (IgE) to attack the pollen. This triggers the release of further chemicals, including histamine, which together cause the symptoms of an allergic reaction.
In England, most people with hayfever are allergic to grass pollen. However, trees, mould spores and weeds can also cause hayfever. Research shows that pollution, such as cigarette smoke or car exhaust fumes, can make allergies such as hayfever worse.
