Billions of people worldwide take medicines every day to treat important diseases. In many cases, however, neither the doctor nor the pharmacist has the time to explain to the patient why a particular drug should be taken, how the drug works and what side effects to expect. Of course, the patient can find everything about a particular drug on the Internet. But how reliable and understandable is this information? In addition, most Internet sources do not point out the interrelationships between different diseases and drug interactions. Written by an experienced and well-known textbook author, this book provides an overview of the most common diseases and the drugs used to treat them. The book is designed for a general audience. It provides patients with essential information about how medications work and what side effects and interactions to expect. Finally, the book gives patients advice on what they can do themselves to improve drug therapy and safety. Summaries, bullet points, tables and diagrams support the information process.