A drug is a chemical substance that can change how your body and mind work. Drugs of abuse are substances that people use to get high and change how they feel. They may be illegal drugs like marijauna (in some states), cocaine, or heroin. Or they may be legal for adults only, like alcohol and tobacco.

Medicines that treat illness can also become drugs of abuse when people take them to get high—not because they’re sick and following their doctor’s orders. People can even abuse cough or cold medicines from the store if they ignore the directions and take too much at one time.

People use drugs for many reasons:

• They want to feel good. Taking a drug can feel really good for a short time. That’s why people keep taking them—to have those good feelings again and again. But even though someone may take more and more of a drug, the good feelings don’t last. Soon the person is taking the drug just to keep from feeling bad.
• They want to stop feeling bad. Some people who feel very worried, afraid, or sad abuse drugs to try to stop feeling so awful. This doesn’t really help their problems and can lead to addiction, which can make them feel much worse.
• They want to do well in school or at work. Some people who want to get good grades, get a better job, or earn more money might think drugs will give them more energy, keep them awake, or make them think faster. But it usually doesn’t work, may put their health at risk, and may lead to addiction.

According to the The Diagnostic and Statistical Manual of Mental Disorders, when someone develops a substance use disorder, they may have a pathological pattern of behaviors related to the use of the substance. They may fit into different groupings such as the following:

• Impaired control: the person may take the substance in larger amounts over a longer period of time; express desire to cut down on use and may have difficulty decreasing or stopping use; and spend a great deal of time acquiring the substance, using it, or recovering from its effects. In more severe cases, virtually all the person’s daily activities revolve around the substance.
• Social impairment: recurrent use of the substance can affect the person’s ability to fulfill obligations at work, school, or home. They continue using even though it has caused interpersonal problems; important social, work, or recreational activities are abandoned or reduced because of the substance use. The person may withdrawal from family activities in order to use the substance.
• Risky use: recurrent substance use in situations where it’s physically hazardous; The person may continue using substance despite regular physical or psychological problems that result from its use.
• Pharmacological criteria: the person develops tolerance, which is marked by increased dose of the substance to achieve desired effect or a significantly reduced effect when the typical dose is consumed. Withdrawal symptoms from the substance which may lead the person to consume the substance to relieve the symptoms.^[1]

Cigarettes and Tobacco

It might surprise you to learn that cigarettes and other forms of tobacco are drugs. It’s legal to use tobacco once you’re eighteen or nineteen years old, depending on where you live. But it’s not healthy for you at any age. Tobacco contains nicotine, a substance that excites the parts of the brain that make you feel good. You can get addicted to nicotine just like other drugs. When you use tobacco, the nicotine quickly gives you a mild rush of pleasure and energy. But it soon wears off, which makes you want to use it some more. Sometimes, the rush of energy that comes with nicotine can make you nervous and edgy.

Read NIDA’s DrugFacts: Electronic Cigarettes (e-Cigarettes) for information about electronic cigarettes, including how safe they are compared to tobacco cigarettes.

Effects of Cigarettes and Tobacco on the Body and Brain

These are just some of the problems cigarettes and tobacco can cause:

• Lung diseases: Cigarette smoke causes lung cancer and painful breathing diseases like emphysema. These diseases can happen to people who smoke, or to others around them who breathe in their smoke.
• Bad breath, bad teeth, mouth cancer: Cigarettes and other kinds of tobacco stain teeth and cause bad breath. Chewing tobacco can make teeth fall out and lead to mouth cancer.
• Heart and blood problems: If you smoke, you are more likely to have a heart attack or stroke (sometimes called a “brain attack”).
• Hurts babies: If a pregnant woman uses tobacco, her baby might be born too early or too small and can cause health problems for the baby.
• More diseases: Using cigarettes or other kinds of tobacco can lead to heart disease and many kinds of cancer.
• Addiction: The nicotine in tobacco is what makes you addicted. When you smoke, the effects wear off quickly, which makes you want to keep using tobacco again and again throughout the day. The more you use tobacco, the more your body and brain get addicted to the nicotine. Fortunately, there are medicines, other treatments, and hotlines that can help people quit tobacco.