A new synthetic drug, 2C-I, is replacing bath salts as the hallucinogen of choice among teenagers, and while the substance has not led to zombie behavior, it’s been blamed for a number of deaths in the United States.

Police departments are trying to keep up with 2C-I, which has the street name “Smiles,” and warning teens and other users of its effects.

"I think [the drugs] just keep changing to try to circumvent the law," Grand Forks, N.D., Police Department Det. Lindsay Wold told Yahoo Shine. "Anytime we try to figure something out, it changes."

Grand Forks is familiar with 2C-I after an 18-year-old from the city, Christian Bjerk, overdosed on the drug and died on a sidewalk, according to CityPages.

Bjerk’s death was linked to a tainted batch of Smiles, East Grand Forks Police Department Lt. Rod Hajicek told the website.

The bad drugs “"seems to be isolated to the Grand Forks-East Grand Forks area right now, but anytime we have two individuals dead within a couple days of each other, that certainly gets our attention."

Hajicek was referring to Elija Stai, 17, of nearby Park Rapids, N.D., who died after ingesting 2C-I mixed with melted chocolate.

Stai was given smiles by a friend, 18-year-old Adam Budge, who now faces 25 years in prison after being charged with providing the 2C-I to the teen.

Budge, of East Grand Forks, was charged with murder, manslaughter and controlled substance charges, according to WDAY.

Witnesses who saw Stai after he ingested 2C-I said he was “shaking,” “growling,” and “foaming at the mouth,” when he then “started to smash his head against the ground” and looked possessed, according to Yahoo Shine.

Stai’s behavior resembled those who were under the influence of bath salts, another synthetic drug that made headlines over the summer.

While bath salts were initially suspected to fuel the actions of so-called “Miami zombie” Rudy Eugene, who ate the face off victim Ronald Poppo, the synthetic drug was not found in Eugene’s system.

But bath salts have been linked to violent and sometimes odd behavior, like the case of a man who broke into an Ohio home and started putting up Christmas decorations.

Since 2C-I is a novel drug, only recently becoming popular in the United States (Smiles first emerged in Europe in 2003,) law enforcement and hospitals face difficulties in detecting the drug because of its synthetic nature.

"The unfortunate thing is if kids who are overdosing on 2C-I go in to the hospital with a physical problem, a lot of times they can't test for it so it doesn't show up as a drug overdose," Wold said.

Those who have experience using the drug often give reviews of 2C-I on YouTube or Internet message boards.

A message board on phantasytour.com is filled with people who endorse 2C-I use while others warn of its dangers.

User dwtk called 2C-I “legit as f--- if you know you’re taking it” and went on to describe his hallucinations while on Smiles.

“[L]ast time i took that s--- i couldnt even see in front of my face because of the visuals but i could walk and talk like i was sober,” they said.

“2ci is pretty weird s--- if you ask me,” said user Golgiiguy. “I found the residual effects a couple days later to not feel right. We got into it when L [LSD] was pretty much nowhere to be found for a number of years. No interest to dabble in the RC [research chemicals] anymore.”

“FYI this s--- is in the ‘lightning bolts,’” opined user Mango99.

User FutureMan discouraged message board members from experimenting with Smiles.

“I have been trying to tell people this for the last yea [sic,]” he said. “My girlfriend is an ER nurse and she has seen some kids come through that have lost limbs and nearly die because of this s---.”