Police say about a dozen people in Newark became ill after ingesting the synthetic marijuana K2.
A state law, enacted four years ago, that bans those products is having some effect.
Bruce Ruck with the New Jersey Poison Education and Information System says since the ban took effect, calls are down to the poison center about the products treated with chemicals designed to mimic the effects of marijuana.
"We have seen those numbers go down somewhat. I think there are other stuff on the market taking its place, hard to say what that is, and as you knock one thing down something else tends to pop up."
Ruck says synthetic marijuana products are dangerous.
"They cause significant agitation, significant hallucinations. They can cause other side effects as well. There are reports in various states where some people have developed renal failure from it. "
Roseanne Scotti with the Drug Policy Alliance says that's a good reason to legalize the recreational use of marijuana in New Jersey.
"Give people safe legal access to marijuana and they're not going to be using these dangerous substances that they're getting from who knows where."
But legalizing recreational use in the state isn't likely anytime soon since Governor Christie opposes it.