What Is Drug Addiction? Addiction is a disease that affects your brain and behavior. When you’re addicted to drugs , you can’t resist the urge to use them, no matter how much harm the drugs may cause. Drug addiction isn’t about just heroin , cocaine , or other illegal drugs . You can get addicted to alcohol , nicotine, opioid painkillers, and other legal substances. At first, you may choose to take a drug because you like the way it makes you feel. You may think you can control how much and how often you use it. But over time, drugs change how your brain works. These physical changes can last a long time. They make you lose self-control and can lead you to damaging behaviors. Addiction vs. Abuse Drug abuse is when you use legal or illegal substances in ways you shouldn’t. You might take more than the regular dose of pills or use someone else’s prescription. You may abuse drugs to feel good...