Antivirals and antibiotics belong to the most important drugs worldwide. In chapter 1 bacteria are generally discussed. The second chapter deals with an overview of the various representatives of the antibiotics as well as the historical background and resistances. Chapter 3, 4, 5, and 6 examine the individual representatives and their different active pharmaceutical ingredients in more detail. The special cases in the antibiotic therapy such as pregnant women, children, liver and kidney patients are described in chapter 7. Chapter 8 contains a short overview of proposals to the antibiotic therapy. Viruses are presented in chapter 9. Their structure, reproduction as well as pathogenic viruses are shown here. Finally, in Chapter 10 medically treatable viruses and the related therapies are listed.