Methylene Blue (MB) is a blue dye first developed by a German scientist, Heinrich Cato in 1876. Originally used as a textile dye but later found to have medicinal properties. This book discusses the use of MB in clinical medicine. The book also looks at the historical uses of methylene blue, such as in the treatment of malaria.As a dye, it can be used in surgery to highlight structures, such as fistulae. In pathology, it can be used as a tissue stain. In emergency medicine it can be used to treat methaemoglobinaemia, carbon monoxide poisoning as well as vasoplegic shock. In clinical medicine, MB can be used in a variety of conditions as it has anti-inflammatory, antiviral, antibacterial and anticancer properties. MB enhances the activity of the mitochondria and can be used to increase energy. MB can cross the Blood Brain Barrier and has been found to reduce neuroinflammation and can be used in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and a host of other degenerative diseases. Although much of the research has been done in animal models, due to the safety, it can be translated to human use.One great myth is that methylene blue is dangerous. To some extent this is true, however, this can also apply to any drug, vitamin, mineral and herb. Dosage is the key issue. Another key issue is that it is contra-indicated in certain people. Therefore, it is up to the prescribing doctor to determine the correct dose in people who can use it safely Hopefully this book will encourage everyone to look more closely at MB and use it to treat conditions that up till now have no specific treatment.