Although the understanding of the cause of asthma continues to improve in parallel to advancements in the quality and variety of medications available to treat asthma, mortality and morbidity caused by asthma continues to rise in much of the world. Difficult-to-manage asthma may be the result of a variety of causes, including poor adherence to medication and trigger avoidance, the presence of unrecognized exacerbating factors, and improper diagnosis. A thorough evaluation for the cause of resistant asthma facilitates a more rational approach to treating the difficult asthmatic as illustrated in the box below.