Acute upper respiratory tract infections (UR TI, such as coughs and colds, influenza, sinusitis, tonsillitis, other throat infections and middle ear infections) are among the most common illnesses experienced at all ages. These infections lead to absence from school and work, visits to general practitioners (GPs) and heavy use of'over the counter' medicines. In the UK, respiratory infections account for approximately 5.5 million GP visits annually and an estimated cost of f170 million (Health Protection Agency, 2005). These infections are also one of the main reported causes of illness in athletes. For example, analysis of the 126 reported illnesses in athlet es competing at the World Athletics Championships in Daegu, South Korea, in 2011 revealed that 40% ofillnesses affected the upper respiratory tract, with confirmed infection in around 20% of cases (Alonso et aL 2012). Other than sickness associated with exercise-induced dehydration (12%), gastroenteritis/diarrhoea was the next most common illness reported (10%).