Bath Salt Zombies is a 2013 American horror comedy directed by Dustin Mills, written by Mills and Clint Weller, and starring Josh Eal, Ethan Holey, Jackie McKown, Dave Parker, and Brandon Salkil. It is about zombie attacks brought on by concentrated bath salts.
Bath Salts make people thing they are zombies. 
This movie is likely based on a real life bath salt phenomenon where people ingested them and thought they were zombies and tried to eat people.  However most bath salts don't make normal people think they are zombies. However it has happened before. 