The purpose of this book is to provide medical students, postgraduate fellows, general practitioners, and specialists a succinct, easy-to-read, well-illustrated, and comprehensive review of difficult asthma. The book brings together the opinion of international experts in the field and provides a pragmatic overview of the clinical problems, giving an insight into the complexity of this population and providing a framework for managing these patients. It covers the etiology, pathogenesis, and management of refractory asthma and novel therapeutic approaches in this group. Importantly, it gives an insight into the patient’s perspective of severe asthma and the associated disproportionate use of healthcare resources and major economic burden of poorly controlled asthma.