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 medication. 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 with exposure to prescribed medications, or receiving medications from a friend or relative who has been prescribed the medication.
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 (withdrawal symptoms).
You may need help from your doctor, family, friends, support groups or an organized treatment program to overcome your drug addiction and stay drug-free.
Drug use can have a wide range of short- and long-term, direct and indirect effects. These effects often depend on the specific drug or drugs used, how they are taken, how much is taken, the person’s health, and other factors. Short-term effects can range from changes in appetite, wakefulness, heart rate, blood pressure, and/or mood to heart attack, stroke, psychosis, overdose, and even death. These health effects may occur after just one use.
Longer-term effects can include heart or lung disease, cancer, mental illness, HIV/AIDS, hepatitis, and others. Long-term drug use can also lead to addiction. Drug addiction is a brain disorder. Not everyone who uses drugs will become addicted, but for some, drug use can change how certain brain circuits work. These brain changes interfere with how people experience normal pleasures in life such as food and sex, their ability to control their stress level, their decision-making, their ability to learn and remember, etc. These changes make it much more difficult for someone to stop taking the drug even when it’s having negative effects on their life and they want to quit.
Drug use can also have indirect effects on both the people who are taking drugs and on those around them. This can include affecting a person’s nutrition; sleep; decision-making and impulsivity; and risk for trauma, violence, injury, and communicable diseases. Drug use can also affect babies born to women who use drugs while pregnant. Broader negative outcomes may be seen in education level, employment, housing, relationships, and criminal justice involvement.
For more information on how various drugs affect different parts of the body and disease risk, select an option in the Contents.
Drug addiction symptoms or behaviors include, among others:
- Feeling that you have to use the drug regularly — daily or even several times a day
- Having intense urges for the drug that block out any other thoughts
- Over time, needing more of the drug to get the same effect
- Taking larger amounts of the drug over a longer period of time than you intended
- Making certain that you maintain a supply of the drug
- Spending money on the drug, even though you can’t afford it
- Not meeting obligations and work responsibilities, or cutting back on social or recreational activities because of drug use
- Continuing to use the drug, even though you know it’s causing problems in your life or causing you physical or psychological harm
- Doing things to get the drug that you normally wouldn’t do, such as stealing
- Driving or doing other risky activities when you’re under the influence of the drug
- Spending a good deal of time getting the drug, using the drug or recovering from the effects of the drug
- Failing in your attempts to stop using the drug
- Experiencing withdrawal symptoms when you attempt to stop taking the drug.