Marijuana is a euphoriant that can cause sedation or dysphoria
in some users. Overdose does not occur. Psychologic dependence
can develop with chronic use, but very little physical
dependence is clinically apparent. Withdrawal is uncomfortable
but requires only supportive treatment. Marijuana is the most
commonly used illicit drug; it is typically used episodically
without evidence of social or psychologic dysfunction. In the
US, marijuana is commonly smoked in cigarettes, made from the
flowering tops and leaves of the dried plant, or as hashish, the
pressed resin of the plant. Much less commonly, marijuana is
taken orally. Dronabinol, a synthetic oral form of the active
ingredient, Δ-9-tetrahydrocannabinol (THC), is used to treat
nausea and vomiting associated with cancer chemotherapy and to
enhance appetite in AIDS patients. Δ-9-THC binds at cannabinoid
receptors, which are present throughout the brain. Any drug that
causes euphoria and diminishes anxiety can cause dependence, and
marijuana is no exception.