Nicotine is one of 4,000 chemicals found in tobacco. Nicotine can act on the body as both a stimulant and a depressant. Inhaled in short puffs, nicotine is a stimulant, but when deeply smoked, it has a tranquilizing effect. Most smokers use it for both effects. The U.S. government considers nicotine to be as addictive as alcohol, cocaine, and morphine. Nicotine is addictive because it increases dopamine, a chemical related to the desire to consume drugs, and because it activates the brain’s reward pathways. Nicotine can boost mood and alleviate depression, and it can stimulate memory and alertness. But it also raises blood sugar levels, increases insulin, heart rate, blood pressure and bowel activity and decreases appetite. Because these effects burn more calories, weight gain is possible after quitting tobacco use. An estimated 443,000 people in the U.S. die every year from tobacco-related diseases. Pregnant women who smoke put their babies at risk for lung problems and low birth weights. Secondhand smoke is also dangerous. Nonsmokers who live with smokers increase their risk for lung cancer by 25 percent.
Giving up smoking can be a difficult and unpleasant process. Nicotine withdrawal symptoms include headache, depression, tobacco cravings, irritability, difficulty concentrating, anxiety, increased appetite, and weight gain. Many use “nicotine patches” which provide a continuous dose of nicotine that gradually decreases to zero. Prescription medications include bupropion (brand names: Wellbutrin, Zyban), varenicline (brand name: Chantix) and antidepressants such as Prozac. Many people who abuse illegal drugs and alcohol are also smokers. This may be related to genetic factors that make certain people prone to addictions. Some rehab centers treat smoking and other substance dependency at the same time, but one study found that about one in three smokers will leave treatment early if asked to go through both treatments simultaneously.