Why does flakka drive people crazy?
Flakka, like bath salts, is a type of synthetic cathinone: a drug chemically similar to amphetamines, whose mechanism of action on the brain isn't entirely clear. In addition to the paranoia and hallucinations, the most violent reactions to these drugs are often referred to as a sort of "excited delirium" -- which is a fancy way of saying you're so agitated & violent that chewing someone's face seems like a perfectly normal thing to do.
So how is flakka different from bath salts?
Technically, the two are chemically distinct variations within the same synthetic cathinone family, but thanks to the overall shady nature of these drugs it's quite common for flakka to be included as an active ingredient in whatever's being sold as "bath salts," so there's a fair bit of overlap. Really, though, the fact that "bath salts" is already a misnomer should indicate that you're probably not getting what you think you're getting.
How common is flakka?
According to the DEA, Flakka use skyrocketed over the last few years, from 85 cases in 2012 to over 670 in 2014 -- that said, flakka-related arrests and deaths have reportedly seen a remarkable decline in South Florida, one of the areas worst-hit by the drug. Of course, if the aforementioned brutal murder in Martin County does turn out to be the result of a flakka overdose, those statistics will likely have to change.