Chemicals which may be used for the treatment of diseases and for reducing the suffering from pain are called medicines or drugs. The branch of science which makes use of chemicals for the treatment of diseases [therapeutic effect] is called chemotherapy. Chemotherapy is the use of chemicals for therapeutic effect. Drugs interact with target molecules, i.e. biological macromolecules such as carbohydrates, lipids, nucleic acids, and proteins. Drugs are designed in such a way that they interact with specific targets only to minimize the side effects. Releasing mental stress, destroying microbes/arresting microbes, preventing the body from infectious diseases, etc. is taken care by drug chemistry.