Pain medicine is the branch of medicine dealing with the management of pain for improving the quality of life of patients suffering from pain. When a pathology is resistant to treatment and pain persists, and when the underlying cause of pain can not be understood, the task of pain medicine is to relieve suffering. An important goal of pain management is to address pain in such a way that it is effective and causes as little side effects as possible. NSAIDs, opioids, muscle relaxants, antiepileptic and anti-inflammatory drugs, cannabinoids, antidepressants, anticonvulsants, etc. are medications that are prescribed for mild, acute, severe and chronic pain. For the treatment of chronic pain, whether due to malignant or benign processes, a three-step Analgesic Ladder recommends the kind of prescription for mild, moderate and severe pain and the way to increase analgesia. This book presents the complex subject of pain medicine in the most comprehensible language. From theories to research to practical applications, case studies related to all contemporary topics of relevance to this field have been included in this book. With state-of-the-art inputs by acclaimed experts of this field, this book targets students and professionals.