K2 and Spice came onto the market as an alternative for marijuana. Where marijuana was illegal, K2 and Spice were not, nor did they cause people to fail drug tests. What producers did not tell the public is that these items could alter moods, cause depression and hallucinations, and cause breathing and respiratory problems.
While there are some extreme examples of negative reactions to K2 Spice, these effects were not widespread and there are extreme examples of negative reactions to just about everything. It has generally been found that natural cannabis is safer and less likely to cause side effects, but there is no evidence that K2 Spice is actually dangerous for the general population.