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. Addiction is when you can’t stop. Not when it puts your health in danger. Not when it causes financial, emotional, and other problems for you or your loved ones. That urge to get and use drugs can fill up every minute of the day, even if you want to quit.