Synthetic marijuana killed three times more people in the first five months of 2015 than in the same period of 2014, the U.S. Centers for Disease Control and Prevention (CDC) said on Thursday.
With catchy "brand" names such as Spice, Sexy Monkey, Black Mamba, K2, No More Mr. Nice Guy, Twilight and hundreds of others, synthetic marijuana is not the same as naturally grown cannabis.
These addictive designer drugs, which are easily available and often sold at small retail outlets and via the Internet as herbal products, consist of psychoactive chemicals or a mixture of chemicals that are sprayed on to plant material and then smoked or ingested to produce a "high".
Although the dangers are widely publicized, synthetic marijuana is gaining in popularity, particularly among teenagers and young adults, the CDC said.
The Obama Administration's "Synthetic Drug Abuse Prevention Act" signed in 2012 specifically prohibits the sale or possession of some of these synthetic cannabinoids, but makers are adept at tweaking chemical compositions to circumvent laws.
Between January and May 2015, 48 U.S. poison centers reported 15 deaths associated with synthetic cannabinoid use, compared with just five in 2014, the CDC said in its report.
The agency also reported a 229 percent spike in related calls to U.S. poison centers between January and May, compared with the same period of 2014.
The most common side-effects of the drugs include agitation, rapid heart beat, drowsiness, lethargy, vomiting, and confusion.
Plant material laced with synthetic cannabinoids was first reported in the United States in December 2008, when a shipment of "Spice" was seized and analyzed by U.S. Customs and Border Protection officials in Dayton, Ohio, according to the Office of National Drug Control Policy.
Data from the American Association of Poison Control Centers shows that the number of closed cases related to people exposed to these drugs stood at 3,822 through June 10, already above the 2014 total of 3,682. (bit.ly/1GAtLQ8)
(This story corrects to show comparison is with same period of 2014, not all of 2014)
(Reporting by Natalie Grover in Bengaluru; Editing by Simon Jennings)