Drug abuse refers to using drugs in a way that deviates from approved medical use, while drug addiction involves compulsive drug use that takes priority over other activities. Commonly abused drugs include depressants like alcohol and barbiturates, stimulants like cocaine and amphetamines, hallucinogens like LSD, marijuana, inhalants, and steroids. Cocaine works by blocking the reuptake of dopamine and other neurotransmitters, while morphine acts on opioid receptors to inhibit adenylate cyclase and produce sedation. Counseling patients and encouraging lifestyle changes can help those struggling with drug abuse and addiction.