Clin Med
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Asthma is a heterogeneous condition with multiple phenotypes that respond to treatments in different ways. Allergic asthma is an important phenotype and although currently available treatments are effective, about 5% of affected patients have severe, treatment-refractory disease. ⋯ Clinical trials are ongoing with novel biologic agents that demonstrate potential efficacy; determining the subsets of patients for which they are suitable will be crucial to ensure cost effectiveness. Personalised medicine and targeted therapies may hold the key to long-term control in this group of patients.