The difference between substance abuse and addiction is very slight. Substance abuse means consuming an illegal substance or using a legal substance incorrectly. The addiction begins as abuse, or consuming substances such as marijuana or cocaine. You can use a drug (or alcohol) without having an addiction. For example, just because Sara has smoked marijuana a few times does not mean that she has an addiction, but it does mean that she has used a drug, and this can lead to an addiction. People can get addicted to all kinds of substances. When we think of an addiction, we usually think of alcohol or illegal drugs. But people can become addicted to drugs, tobacco, even glue. And some substances are more addictive than others: drugs like crack or heroin are so addictive that trying them once or twice may be enough to make the person using them lose control. Addiction means that a person cannot control their desire to use a drug or drink. Someone who is addicted to cocaine has become so used to the drug that he cannot stop using it. Addiction can be physical, psychological, or both. Physical addiction Being physically addicted means that a person's body becomes dependent on a particular substance (even smoking can be addictive). It also increases the person's tolerance to that substance, so that the person needs an increasing dose to obtain the same effect. Someone who is physically addicted and stops using a substance, such as drugs, alcohol, or tobacco, experiences a withdrawal syndrome. Some symptoms of withdrawal syndrome are diarrhea, tremors, and feeling lousy in general. Psychological addiction Psychological addiction occurs when the urge to use a drug is psychological or emotional. People who are psychologically addicted feel that the desire to use a drug overwhelms them. They can lie and even steal to get it. A person crosses the line between drug use and addiction when they no longer use the drug for fun or to "get high," but have become dependent on it. His life centers on his need for the drug. An addicted person — whether they have a physical or psychological addiction or both — feels that they cannot stop using the drug.