Among adults, cigarette smoking causes heart disease a nd stroke. Studies have shown that early signs of these diseases can be found in adolescents who smoke. Teenage smokers suffer from shortness of breath almost three times as often and produce phlegm more than twice as often as teens who don't smoke. Several studies have found nicotine to be addictive in ways similar to those of heroin, cocaine, and alcohol. The transition from experimentation to dependence occurs just as frequently among young smokers as it does among users of cocaine and heroin.
Young people tend to underestimate the addictiveness of nicotine .
Of people who were daily smokers in high school but who planned to stop smoking, almost 75 percent were still smoking 5 or 6 years later. Teen smoking is often an early warning sign of future problems . Teens who smoke are three times as likely as nonsmokers to use alcohol, eight times as likely to use marijuana, and 22 times as likely to use cocaine. Smoking is also associated with numerous other risky behaviors, including fighting and having unprotected sex. It gets even scarier than that.