Smokers who are addicted to tobacco report a range of positive sensations that come from smoking a cigarette. These range from reduced tension or appetite to a heightened sense of well-being. Researchers trace these sensations back to the flood of chemicals released into the nervous system by nicotine. Just like any prescription or illicit drug, it changes the body's chemistry and functioning when it enters the system.
For some, smoking is essentially a way to self-medicate for illnesses that cause tension and pain. Patients suffering from some forms of mental illness, such as depression or anxiety disorders, may take up smoking because it can help mitigate some of their symptoms [source: Lillard].
But as is the case with many powerful drugs, using nicotine to manage medical conditions comes with a host of negative side effects. Beyond addiction, the risks of lung disease, cancer, heart disease and early death mean nicotine, while potentially effective in treating some disease symptoms, is truly a double-edged sword when used to self-medicate.