Tetrahydrocannabinol (THC), is the principal psychoactive constituent (or cannabinoid) of the cannabis plant. THC has mild to moderate analgesic effects, and cannabis can be used to treat pain. Other effects include relaxation, alteration of visual, auditory, and olfactory senses, fatigue, and appetite stimulation. THC has marked antiemetic properties. It may acutely reduce aggression and increase aggression during withdrawal.