It produces sensations similar to tetrahydrocannabinol (THC), the psychoactive ingredient in the cannabis plant, yet many users report more powerful, often dangerous effects.
To understand the overall behavior of fake weed users, Heather Clayton, lead researcher of the new study and a health scientist in the CDC's Division of Adolescent and School Health, turned to the 2015 Youth Risk Behavior Survey, a school-based anonymous questionnaire administered to a nationally representative sample of high school students.
A total of 15,624 students in grades nine through 12 reported their behavior in four domains: substance use, injury and violence, mental health and sexual health.
"We learned from the 2015 Youth Risk Behavior Survey that nearly one in 10 high school students had used synthetic marijuana at some point in their lifetime," Clayton said.
Of these students, nearly all reported that they had also used marijuana at least once. They were more likely to use marijuana very early in life -- before the age of 13 -- compared with students who had only ever used marijuana, according to Clayton.
Almost two-thirds of the surveyed students said they'd never used marijuana or synthetic cannabinoids.
But nearly a third of the students reported trying or routinely using marijuana, while about 23% of these students had also tried or used fake weed.
Digging deeper into the data, Clayton and her colleagues discovered that students partial to synthetic cannabinoids were significantly more likely to perform risky sexual behaviors compared with students who limited themselves to marijuana.
For instance, compared with just 2% of nonusing teens and about 5% of marijuana-using teens, nearly 15% of fake weed-using teens had their first sexual intercourse before age 13. And about 38% of these same teens had had intercourse with four or more people, compared with just 3% of the nonusers and 20% of the students using cannabis.
Violence was also more prevalent among teens partial to fake weed. A third of fake weed users had carried a weapon, compared with 12% of nonusers and about 19% of weed users. Meanwhile, more than half of fake weed users had been in physical fights and a quarter drove while drinking, compared with nonusers (15% and 2%, respectively) and weed users (29% and 12%, respectively).
"The findings indicate that students who report using synthetic marijuana are possibly on a very concerning health trajectory, which is particularly serious given that synthetic marijuana use is relatively common among adolescents," Clayton said.
Based on the research, she and her colleagues believe school programs and health professionals should feature not only marijuana but synthetic cannabinoids in their prevention strategies.
Depression and other risk factors
Packages labeled as a safe and "natural" blend of herbs may give a false impression that the drug is a safe alternative to marijuana. Yet fake weed has caused rapid pulse, lethargy, nausea, vomiting, agitation, chest pain, hallucinations, delusions, confusion and dizziness, according to poison center reports.
The most severe effects reported include seizures, permanent cardiovascular damage, liver damage, stroke, psychosis, paranoia, aggression, anxiety attacks, dependence and death through overdose, suicide or an extreme negative reaction.
With so many obvious dangers, Andrew Ninnemann, a doctoral student in the clinical psychology program at the University of Maryland, designed a separate study, also published Monday in the journal Pediatrics
, to understand the risk factors that contribute to a teen using fake weed.
Ninnemann and his colleagues recruited nearly a thousand students from seven public schools in Texas to participate in a survey in 2011, with follow-up questions approximately one year later. At the start of the survey, most participants were enrolled in the 10th or 11th grades. Ethnically diverse, 31% of the teens were African-American, 29% were white, 28% were Hispanic, and 12% categorized themselves as "other."
Analysis of the data showed that African-American teens and females were less likely to use fake weed than males and teens of other ethnicities.
Symptoms of depression, alcohol use, marijuana use and fake weed use predicted using fake weed one year later. However, teens with symptoms of anxiety or impulsivity were not likely to report using fake weed later.
The results indicate that using marijuana may increase the risk of fake weed use -- but not vice versa.
"This suggests that synthetic cannabinoid use should not necessarily be thought of as a risk factor for eventual marijuana use but instead may be a risk factor for those adolescents who engage in marijuana use already," Ninnemann said.
'Unpredictable reactions' to a changing substance
"Teens who use synthetic cannabinoids, really, it's playing a game of Russian roulette," said Dr. Robert Glatter, an emergency physician at Lenox Hill Hospital in New York City.
"Typically, they become very aggressive and violent in the ER, and often they require chemical (sedation) if not physical restraint."
The reaction of each user is "unpredictable," Glatter said. "We've had people with seizures requiring airway management and intubation. Other times, they can smoke it and become a little violent, seize once, and that's it. In other cases, they can become a little violent, a little agitated, and that's it. They wake up in a few hours."
Mostly, though, because they are "flailing around" and become violent and aggressive, the main issue is that they can injure the staff and themselves.
"Luckily, we haven't been seeing a whole lot of it in the last six to 12 months. It's kind of quieted down," Glatter said. "A few years ago, we were seeing several cases a week." Still, he said, it's likely to pop up again.
"People talk about getting it in bodegas, head shops, gas stations ... or they buy it from a friend."
Users find it difficult to gauge how much is too much, because once a fake weed formula is recognized, it will be outlawed, but then the producers will quickly change the chemical formula to keep one step ahead of the law.
"This is dangerous and unpredictable, and it can kill you," Glatter said. "Using marijuana, which I'm not condoning, is safer. We don't see the violent behavior or the seizure aspect we see with this drug."
What parents need to know
According to Dr. Scott Krakower, assistant unit chief for psychiatry at Zucker Hillside Hospital in Glen Oaks, New York, parents often ask him whether their teens might be doing permanent damage to their brains.
"It's a tough question," he said. "There is a possibility you can alter the neuro circuitry just from ingesting some of these agents. ... There could be some sustained injury."
It's more likely, he said, that with treatment and help, the brain may be able to recuperate.
Teens using fake weed can become paranoid, on edge, agitated and aggressive toward parents and family members.
"It's a different kind of psychosis than we might see with other patients. The psychosis is an agitated psychosis," Krakower said. "They're violent. They can become aggressive. It is very scary, if you've ever seen these kids on it.
"And coming off of it is very, very scary, too. It takes them a few days sometimes to get rid of the paranoia. Sometimes, they'll be paranoid for like 48, 72 hours."
Krakower said the substance emerges in waves while drug officials and test kits try to keep up with changing formulations.
Usually, he tells that parents the warning signs for synthetic cannabinoid use include a child with a history of substance use and drug tests that come back negative even when the child appears high.
"And if they are using synthetic agents, that's pretty serious, and they should definitely seek help from a professional," Krakower said, whether it's an addiction specialist or even a trusted pediatrician who might guide them through the crisis. "There's a lot of ways to tackle this."