If it's wheeze it must be asthma, and if it's asthma it must mean bronchodilators and inhaled corticosteroids—simple enough. Indeed, as asthma is so common this paradigm might seem to be logical. The large scale international study of asthma and allergy in childhood (ISAAC) found that the United Kingdom, Australia, and New Zealand had among the highest prevalences, with 15% of children affected.1 Asthma is more complicated, however, especially in children. We are often uncertain whether children who wheeze do have asthma, and some people say that diagnosing asthma in very young children is not possible. An increasing body of evidence suggests that asthma is a complex disorder and that different patterns of illness have different underlying pathogenesis.

Many studies have investigated various treatments in older children with classic allergic asthma, yet relatively few have considered the many young children who have recurrent wheeze. Many common treatments now have a good evidence base, but gaps still exist, such as treatments for the most difficult and severe childhood asthma. Therapeutic advances include both new drugs and new licences for older drugs. For example, the new drug omalizumab and montelukast are now licensed down to 6 months of age. Yet despite …