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.

There are effective and FDA-approved medications to treat some substance use disorders, particularly opioid use disorders, tobacco use disorder, and alcohol use disorder. Therapy and behavioral health treatment is proven to treat substance use disorders, and is often combined with medication.