About Marijuana Marijuana is the most widely used illicit drug in the United States and tends to be the first illegal drug teens use. However, this is not to say that the majority of teens use marijuana. Additionally, most marijuana users do not go on to use other illegal drugs.
Marijuana has several negative physical and mental effects.
Use of marijuana may impair or reduce short-term memory and comprehension, alter sense of time, and reduce ability to perform tasks requiring concentration and coordination, such as driving a car. Some people who are shy in social situations who turn to marijuana to loosen up, frequently end up making fools of themselves and doing things that they later regret.