"Clemson University Professor John Huffman is credited with first synthesizing some of the cannabinoids, such as JWH-018, now used in 'fake pot' substances such as K2. The effects of JWH-018 can be 10 times stronger than those of THC. Dr. Huffman is quoted as saying, 'These things are dangerous—anybody who uses them is playing Russian roulette. They have profound psychological effects. We never intended them for human consumption.'23 While synthetic cannabinoids may be used with the intention of getting a marijuana-like high, their actual effects are not yet known. Some reported effects of synthetic cannabinoids, such as relaxation and reduced blood pressure, are consistent with effects of marijuana. Other reported effects, such as nausea, increased agitation, elevated blood pressure, and racing heart rates, are not.24 The Centers for Disease Control and Prevention (CDC) has noted epidemiological links between synthetic cannabinoid use and acute kidney injury.25 In at least one case, synthetic cannabinoid use has been blamed for a fatality when an Iowa teen committed suicide reportedly following a K2-induced panic attack.26 In the summer of 2014, the New York City (NYC) Department of Health issued a warning to the public regarding the dangers of synthetic cannabinoid use after 15 people experienced “severe adverse reactions after suspected ingestion of synthetic cannabinoids” over a period of three days.27 In 2015, following a “tenfold increase in medical emergencies from synthetic marijuana” in New York State (NYS) in the summer of 2015 compared to the summer of 2014, Governor Cuomo announced passage of emergency NYS Health Department regulations to combat the sale of these drugs—these emergency regulations included the addition of two classes of chemical compounds to the banned substances list.28"

Source

Sacco, Lisa N. and Finklea, Kristin M., "Synthetic Drugs: Overview and Issues for Congress," Congressional Research Service, Washington, DC: Library of Congress, May 3, 2016.