Which substance is classified as a stimulant?

Cocaine is classified as a stimulant because it acts primarily on the central nervous system to increase energy, alertness, and attention. Stimulants enhance the activity of neurotransmitters in the brain, particularly dopamine, leading to increased feelings of euphoria and heightened cognitive function.

In contrast, alcohol is a depressant that slows down brain function and impairs cognitive and motor functions. Heroin is an opioid, which also acts as a depressant by binding to opioid receptors that help to relieve pain and produce a sense of relaxation and euphoria. Fentanyl, like heroin, is also an opioid and has similar depressant effects on the central nervous system. Thus, while alcohol, heroin, and fentanyl are associated with sedative or depressant effects, cocaine stands out as a stimulant that significantly excites the nervous system.