Respiratory allergy is an umbrella term that includes allergic rhinitis (where the inside of the nose and nasal passages become irritated and inflamed) and allergic asthma (where the lower airways of the lungs become inflamed and swollen). The condition can worsen over time if not treated – e.g., allergic rhinitis is considered to be one of the major risk factors in the development of asthma if left untreated. The prevalence of respiratory allergies has increased over recent decades and is rising dramatically in both developed and developing countries. Allergies are caused by an overreaction of the body’s immune system to substances that would otherwise be harmless. Common triggers of respiratory allergies include pollens, house dust mites, moulds and animal dander. Exposure can lead to a range of symptoms, including allergic rhinitis (inflammation of the upper airways), conjunctivitis (itchy, watery eyes), and allergic asthma (inflammation of the lower airways). For many people, respiratory allergies have a significant impact on their quality of life, causing sleepless nights, shortness of breath and resulting in millions of lost school and work days around the world. Evidence also suggests that having one allergy greatly increases the chances of developing another, and that someone with a respiratory allergy has an increased risk of going on to develop asthma, adding to the cost burden this disease places on society.