Drug addiction, also called substance use disorder, is a disease that affects a person’s brain and behavior and leads to an inability to control the use of a legal or illegal drug or medicine. Substances such as alcohol, marijuana and nicotine also are considered drugs. When you’re addicted, you may continue using the drug despite the harm it causes.

Drug addiction can start with experimental use of a recreational drug in social situations, and, for some people, the drug use becomes more frequent. For others, particularly with opioids, drug addiction begins when they take prescribed medicines or receive them from others who have prescriptions.

The risk of addiction and how fast you become addicted varies by drug. Some drugs, such as opioid painkillers, have a higher risk and cause addiction more quickly than others.

As time passes, you may need larger doses of the drug to get high. Soon you may need the drug just to feel good. As your drug use increases, you may find that it’s increasingly difficult to go without the drug. Attempts to stop drug use may cause intense cravings and make you feel physically ill. These are called withdrawal symptoms.

Help from your health care provider, family, friends, support groups or an organized treatment program can help you overcome your drug addiction and stay drug-free.