Substance use disorder is a chronic and relapsing condition characterized by compulsive drug or alcohol use despite the negative consequences that it causes. Substance use disorder involves both physical and psychological dependence on a substance, which can lead to tolerance (needing more of the substance to achieve the desired effect) and withdrawal symptoms (experiencing unpleasant physical and psychological symptoms when trying to stop or reduce substance use).

Substances that can lead to substance use disorder include alcohol, opioids (such as heroin and prescription painkillers), stimulants (such as cocaine and methamphetamine), benzodiazepines (such as Valium and Xanax), and marijuana, among others. Treatment for substance use disorder typically involves a combination of medication-assisted therapy, behavioral therapy, and support groups.