The Physical and Psychological Effects of Marijuana Marijuana has been used as a drug since the beginning of time, yet there are still many mysteries about its health effects on humans. Marijuana, or cannabis sativa, is a preparation of the crushed flowers and buds of female hemp plant. The existence of the plant has been reported as early as 1500-1200 BC. in China, and cannabis has been described as an analgesic as early as 200 AD . Since then, an overwhelming number of studies have attempted to explain the physical and psychological effects of cannabis on humans. Physical Effects Physically, cannabis is relatively harmless. Studies have obse