Hay fever is caused by an allergic reaction to pollen. When it comes into contact with the mouth, eyes, nose or throat, the body reacts by making specific antibodies. Hay fever affects people at different times depending on which pollen they are allergic to. The majority of people are allergic to grass pollen, while others are affected by weed and mould pollens.
The condition is characterised by sneezing and coughing, a runny or blocked nose, red watery eyes, itchy throat, mouth, nose, eyes or ears, headaches and sometimes a feeling of fatigue or tiredness. Sufferers may also experience a wheeze and tightness in the chest.