What makes marijuana a drug?

Marijuana has an active substance called tetra-hydro-cannabinol (THC) that gives the user the "high" associated with marijuana. Without this substance, marijuana would do nothing to the user. Marijuana is considered a drug because THC induces altered states of consciousness, like alcohol or caffiene, or cocaine. For a substance to be considered a drug it must have a direct effect on one of the systems within your body. Marijuana affects the central nervous system, which is made up primarily of the brain and an intricate network of nerves that run throughout your body. Marijuana is also considered a drug because the FDA and the federal government do not want you using it.