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- Cannabis refers to a genus of flowering plants, including three separate species: C. sativa, C. indica and C. ruderalis.  Cannabis is widely consumed for its intoxicating effects, and it is the most commonly used illicit substance in the world. Street names for cannabis are numerous, and include: marijuana, pot, weed, herb, buddha, nugs, grass, trees, Mary Jane. Cannabis is most often consumed by smoking dried plant material (typically the flower, but leaves may also be included), but vaporization and oral administration is also fairly common. Sometimes cannabis is processed by removing and compressing resin from the plant (called hashish or hash), or by extracting psychoactive cannabinoids using ethanol, butane, or other solvents (called tinctures, hash oil, or infusion products).   Roughly 100 different chemical constituents have been identified in the cannanis plant. The primary psychoactive component is Δ9 -tetrahydrocannabinol, also called Δ9-THC or simply THC. THC exhibits its psychoactive effects via agonism of the cannabinoid type 1 (CB1) receptor.
- In clinical settings, cannabis intoxication involves disruptive behavioral or psychological changes after cannabis use, with expected physical changes, +/- perceptual disturbances .
- Cannabis withdrawal refers to disruptive signs and symptoms of abstinence, including physical symptoms, that occur in heavy users .
- Cannabis use disorder refers to disruptive overuse of the drug. Besides overuse, elements of cannabis use disorder may include loss of control, wasted time, a strong drive to use, social disruption, dangerous use, use despite problems in various areas, tolerance, and withdrawal symptoms .