"It has been estimated that a typical chewing session of khat results in the absorption of its active constituents with an activity equivalent to that of approximately 5 mg of amphetamine.81 The pharmacological effects of khat resemble those of amphetamine use, and includes increased alertness, euphoria, hyperthermia, anorexia, increased respiration rate, heart rate and blood pressure.82
"Fatalities associated with the sole consumption of khat have not yet been reported. However, prolonged use of khat has been linked to adverse effects that range from psychiatric disturbances (from psychosis to depression) to damage of major organs of the body, as well as to similar neurological disorders to those associated with amphetamine and cocaine use.83"

Source

UN Office on Drugs and Crime, "The Challenge of New Psychoactive Substances: A Report from the Global SMART Programme" (Vienna, Austria: UNODC Laboratory and Scientific Section, March 2013), pp. 13-14.
http://www.unodc.org/document…