Illegal Drugs. When people talk about a "drug problem," they usually mean abusing legal drugs or using illegal drugs, such as marijuana, ecstasy, cocaine, LSD, crystal meth, and heroin. (Marijuana is generally an illegal drug, but some states allow doctors to recommend it to adults for certain illnesses.)

SOURCE: kidshealth.org/en/kids/know-drugs.html

Drugs are chemicals that change the way a person's body works. You've probably heard that drugs are bad for you, but what does that mean and why are they bad?

Medicines Are Legal Drugs

If you've ever been sick and had to take medicine, you already know about one kind of drugs. Medicines are legal drugs, meaning doctors are allowed to prescribe them for patients, stores can sell them, and people are allowed to buy them. But it's not legal, or safe, for people to use these medicines any way they want or to buy them from people who are selling them illegally.

Cigarettes and Alcohol

Cigarettes and alcohol are two other kinds of legal drugs. (In the United States, adults 18 and older can buy cigarettes and those 21 and older can buy alcohol.) But smoking and excessive drinking are not healthy for adults and are off limits for kids.

Illegal Drugs

When people talk about a "drug problem," they usually mean abusing legal drugs or using illegal drugs, such as marijuana, ecstasy, cocaine, LSD, crystal meth, and heroin. (Marijuana is generally an illegal drug, but some states allow doctors to recommend it to adults for certain illnesses.)

Why Are Illegal Drugs Dangerous?

Illegal drugs aren't good for anyone, but they are particularly bad for a kid or teen whose body is still growing. Illegal drugs can damage the brain, heart, and other important organs. Cocaine, for instance, can cause a heart attack — even in a kid or teen.

While using drugs, people are also less able to do well in school, sports, and other activities. It's often harder to think clearly and make good decisions. People can do dumb or dangerous things that could hurt them — or other people — when they use drugs.