This book covers various aspects of a respiratory system disorder associated with prescribed drugs that do not yet have established treatment guidelines, and for which the only treatment is to discontinue taking the drug. Very little clinical evidence regarding the disorder is available, since randomized trials cannot to be carried out, the onset of the disorder cannot be predicted, and the resulting pathological condition is life-threatening. However, the need for an established treatment continues to grow due to the introduction of many new drugs, such as anti-neoplastic drugs, biological products, and molecular target drugs, the adverse effects of which are difficult to differentiate from those of other lung diseases, such as lung infectious diseases.