A heroin addict smokes heroin in Lamu November 21, 2014.  REUTERS/Goran Tomasevic Thomson Reuters
Synthetic marijuana, also referred to as "replacement cannabis," "K2," and "Spice," is a lab-produced mind-altering drug that aims to mimic the effects of marijuana, but is known to have unpredictable and sometimes dangerous effects, despite its marketing as a safe, legal alternative to marijuana.