Bath salts

Assuming we're not talking about the stuff you put in the bath to smell nice and/or ease sore muscles, bath salts is a euphemistic term for a variety of manufactured "legal highs" and some illegal drugs.

The phrase "bath salts" has been used by various manufacturers and retailers to sell these products over the counter without drawing too much attention to the fact that they are in fact peddling narcotics.

Mode of action
Bath salts typically contain a cocktail of drugs. For example, synthetic marijuana and asthma medication, with methylenedioxypyrovalerone (MDPV) and the synthetic compounds known as cathinones as their primary ingredients. The synthetic cathinones are derived from the khat plant.

The cathinones mephedrone and methylone act like ecstasy, making nerve cells release more dopamine. The other major ingredient, methylenedioxypyrovalerone (MDPV), is like cocaine and blocks the reuptake of dopamine and norepinephrine. By itself, MDPV is about 10 times more potent than cocaine.

Scientific studies and media reaction
Studies on rats have suggested MDPV may be more addictive than meth. MDPV, one of the active ingredients in bath salts, was banned by the DEA in 2011. Long-term effects appear to be damage to the brain's connectivity, which may explain some of the stranger stories associated with use. Despite its association on the news with cannibalism, the scientific consensus is that despite the drug's extreme addictiveness and potential for brain damage, it does not turn people into zombies.