UPDATE: Since this piece was originally published, use of synthetic marijuana (known as “K2” or “spice”) has skyrocketed. Already this year, the American Association of Poison Control has reported 5,053 exposures to the drug. In all of last year, there were just 4,377. The drug is on the schedule I substance list and has not been tested for safety.

K2. Spice. Black Mamba. Skunk. Bombay Blue. Genie. Zohai Orange. Blaze. Red X. Dawn. Mr. Nice Guy. There are roughly 450 synthetic cannabinoid compounds to go around—pick your poison.

This week, researchers at The University of South Florida unveiled a study that officially links synthetic cannabinoids—most commonly referred to as K2 or Spice—to strokes in “otherwise healthy adults.” The news isn’t groundbreaking; reports of negative reactions to K2 have been surfacing for the past five years. But for those who mistake fake pot for a harmless substitute that will allow them to bypass a drug test, it’s a crude awakening. Doubly so since the DEA just moved to ban three more synthetic drugs, signaling a widening crackdown on the designer drug market.

Marketed by websites like herbal-x.com as “a legal spice that can be smoked,” K2 is a psychoactive designer drug that can lead to strokes, brain damage, and even death. Its classification as an artificial form of marijuana is a dangerous misnomer, masking the potentially deadly consequences of a drug that’s rarely been tested on humans. And while the novelty of its recreational use means statistics on its negative effects are scant, high-profile news stories expose the grim reality of consuming a haphazard dose of what is often a haphazard mix of chemicals.

On October 30 in New York City, a 45-year-old homeless man high on K2 attempted to “surf” on top of a moving subway car. He was pronounced dead on the scene shortly after. Three months before, in Amarillo, Texas, an 18-year-old named Jesse High was pronounced dead after consuming synthetic marijuana that he purchased at a local smoke shop called Planet X. His mom is suing the owners. (The store’s owner, Brandon Whisenhunt, has repeatedly turned down media requests for comment. His attorney, Vince Nowak, has publicly defended him, claiming that everyone at Planet X, “down to the lowliest employee,” was aware that K2 was deadly.) The horror stories date even further back. On New Year’s Eve 2011, Nancy Ferreira was called to a Florida emergency room, where she found her 14-year-old son struggling to breathe after suffering close to a dozen seizures. He later told his mom he had spent the evening smoking “Mr. Nice Guy herbal smoking blend.”

According to a report by the American Association of Poison Control Centers published in the Chicago Tribune in 2010, the number of emergency room visits nationwide due to use of synthetic marijuana went from just 13 in 2009 to 567 in the first half of 2010.

Chris Hoyt, an assistant professor at the University of Colorado School of Medicine who wrote a 100-page paper on the topic of synthetic marijuana, was one of many doctors who treated the more than 100 patients who were hospitalized at The University of Colorado Hospital for synthetic marijuana consumption in August, according to the hospital’s media relations. “There were a smattering of reactions,” Hoyt told The Daily Beast. “Some patients came in with racing heart rates and agitation, others with low blood pressure and the inability to stay awake.” In other cases, Hoyt saw uncontrollable vomiting, stomach pain, and severe anxiety. The inconsistency, he says, points to the biggest problem with synthetic marijuana: We don’t know its effect on humans. “This is a moving target for us,” Hoyt says of synthetic cannabinoids.

Synthesized by Clemson professor Dr. John Huffman, synthetic cannabis was developed in a laboratory to assist in the research of AIDS, multiple sclerosis, and chemotherapy. A 1984 study funded by the National Institute on Drug Abuse, resulted in 450 synthetic cannabinoid compounds. Not one of them is deemed safe for human consumption, a disclaimer that is often printed on the packaging to this day. Huffman, who’s been interviewed about the negative effects of a compound he created, is angry at the development. “It is like Russian roulette to use these drugs,” he told WebMd in 2010. “We don’t know a darn thing about them for real. It shouldn’t be out there.”

For the DEA, tasked with controlling hundreds of subtly different chemical compounds, it’s an uphill battle. “New derivatives, new concoctions are being developed as we speak. We're just trying to keep up,” spokesman Rusty Payne told The Daily Beast. In 2011, the DEA placed K2, and four other chemicals used to make synthetic cannabinoids, on its banned-substances list—a move that gives them 24 months to study the drug, then illustrate to Congress why it’s dangerous. In the past three years, Payne says they’ve added close to 300 substances, many of them chemicals used to make synthetic drugs, to the list of banned substances. But getting actual legislation passed to make them illegal can take years. In the meantime, Payne says a new bill introduced by Senator Dianne Feinstein this July is helping the DEA maneuver around the “grey areas” that result from the ever-changing chemistry of synthetic cannabinoids. The bill allows the DEA to prosecute if they can prove that a synthetic drug shares the same chemistry as one on the banned substances list.

Unfortunately, the prevailing belief among those who sell K2, on places like herbal-x.com, is still that a chemically modified version of a banned substance is legal. “The bad guys think there’s a loophole because they don’t understand the analogue act,” Payne says.

The most recent victim of the synthetic drug chaos is William “Billy” Tucker. Just six months after graduating from Ashland-Greenwood High School, in Nebraska, 18-year-old Tucker went to a party with a few friends at a house in which he ended up staying the night. Around 8:30 the next morning, Tucker’s friends woke him up to say they were heading back to another friend’s house. Feeling exhausted, Tucker decided he was still drunk—leading his friends to suggest he sleep it off in a guest bedroom, according to a report on Omaha.com. A few hours later when one a friend went to wake him, the student described by his mom as “crazy go lucky” was dead. An autopsy report released several days later confirmed that Tucker died of K2. “I can’t fathom it,” his mom told local TV stations. In the wake of his son’s death, Tucker’s dad is running a Facebook page dedicated to spreading awareness about the dangers of K2.

Harmful as it is, the drug is increasingly becoming the hallucinogen of choice for many—its ability to bypass urine drug tests likely a major factor. But to those studied in the world of marijuana, its presence alone is offensive. “It’s nothing like marijuana,” Mark Kleiman, the leader of Washington State’s marijuana legalization program, told The Daily Beast. “People have no experience with these chemicals. When you buy it may say… plant fertilizer...the consumer is completely in the dark.”

It’s not that Kleiman can’t understand the appeal. “If you’re a truck driver, you could lose your license if you test positive for drugs. What do you do if you want to get stoned? You use synthetic cannabinoids,” he says. Still, Kleiman says it’s the criminalization of real marijuana that’s fueling the designer drug fire. Legalized marijuana, he explains, would obliterate the market for synthetic marijuana—making fake pot’s ability to bypass drug tests a moot point. “This is a pure side effect of prohibition,” Kleiman says. “It may not be a good enough reason for getting rid of it, but it’s certainly a reason.”

Editor's Note: An earlier version of this piece named The University of Southern Florida as the location of the study linking synthetic marijuana to strokes. The study was conducted by The University of South Florida.