Marijuana. Drug user smokes a marijuana cigarette (called a joint or reefer). Marijuana is made from the dried leaves & flowering tops of the hemp plant, Cannabis sativa. It can be mixed with tobacco and smoked (as here) or eaten. Marijuana contains a mood-altering (psychoactive) drug, tetrahydrocannabinol (THC). It induces an initial feeling of stimulation followed by sedation and pleasant tranquility. Users may also have altered perceptions of time & space, heightened perception and unusual reasoning patterns. Negative effects can include confusion and anxiety attacks. Frequent marijuana users may develop a psychological dependence on the drug.