Asthma is a common chronic illness in children and young people. It affects, for example, an average of two children in every UK classroom. Initial treatment usually consists of salbutamol used on demand at step 1 of British Thoracic Society (BTS) guidelines. At step 2, regular anti-inflammatory 'controller' therapy starts with the regular use of inhaled corticosteroids such as beclomethasone. Therapeutic efficacy with inhaled steroids usually peaks around 400 micrograms per day of beclomethasone (or equivalent). With inadequate asthma control at step 2, inhaled long-acting β2 agonists (LABA) such as salmeterol, or leukotriene receptor antagonists (LTRA) such as montelukast are added or inhaled corticosteroids are increased; this represents BTS step 3 for asthma management.