According to the CDC, smoking cigarettes kills more than 480,000 people every year in the United States. Smoking also significantly increases your chances of developing lung, throat, and mouth cancers; heart disease; blood clots; and having a stroke. But despite understanding these facts, millions of Americans have difficulty quitting smoking. That’s because the main component of cigarettes (or cigars, vapes, dip, etc.) is nicotine - a highly addictive substance that releases dopamine in the brain, says Dr. Raymond Rezaie.