Spice:
Spice users report experiences similar to those produced by marijuana—elevated mood, relaxation, and
altered perception—and in some cases the effects are even stronger than those of marijuana. Some users report
psychotic effects like extreme anxiety, paranoia, and hallucinations. So far, there have been no scientific studies of Spice’s effects on the human brain, but we do know that the cannabinoid compounds found in Spice products act on the same cell receptors as THC, the primary psychoactive component of marijuana. Some of the compounds found in Spice, however, bind more strongly to those receptors, which could lead to a much
more powerful and unpredictable effect. Because the chemical composition of many products sold as Spice is unknown, it is likely that some varieties also contain substances that could
cause dramatically different effects than the user might expect. What Are the Other Health Effects of Spice? Spice abusers who have been taken to Poison Control Centers report symptoms that include
rapid heart rate, vomiting, agitation, confusion, and hallucinations. Spice can also raise blood pressure and cause reduced blood supply to the heart (myocardial ischemia), and in a few cases it has been associated with heart attacks. Regular users may experience withdrawal and addiction symptoms.
http://www.drugabuse.gov/publications/drugfacts/spice-synthetic-marijuana