Synthetic marijuana is back in the news, with some frightening revelations.
New figures from the Centers for Disease Control and Prevention show synthetic marijuana killed 15 people in the first half of 2015 -- three times as many as the same period in 2014.
Poison control centers across the country have also seen a 229 percent increase in phone calls related to use of the drugs since January.
Synthetic marijuana is a class of designer drugs made up of psychoactive chemicals or a combination of chemicals that are sprayed onto plant material and then smoked or eaten to produce a high. They mimic the effects of THC, the compound naturally found in marijuana, and can be far more potent. Consumers don't know what chemical compounds are in them, so toxicity and health effects vary widely.
Synthetic marijuana can be purchased online or at small retail outlets, where it's often promoted as a natural or herbal product. It comes with catchy names like Crazy Clown, Spice, Black Mamba, and K2.
Despite the evident dangers, synthetic marijuana is becoming more and more popular among teens and young adults.
"A lot of these products are marketed as natural and safe and that could be the appeal," Royal Law, an epidemiologist with CDC's National Center for Environmental Health, told CBS News."A lot of these products avoid illegality by changing chemical compounds and packaging the drug as 'not for human consumption.'"
Most calls to poison control centers concerned use among males with a median age of 26 years. Commonly-reported side effects included agitation, tachycardia (a heartbeat that is too fast), lethargy, vomiting and confusion.
Among 2,961 calls to poison centers, more than 11 percent of callers showed life-threatening signs or symptoms. The report found that another 1,407 callers had moderate effects that were not life-threatening but required treatment.
Law told CBS News that the report highlights the need to increase awareness that synthetic drug use is a serious issue.
"We need to let the public know that if anyone has these products, they need to throw them away," he said. "People using these products have no idea what is in them."