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Synthetic Marijuana - Spice or K2

Medically reviewed by L. Anderson, PharmD. Last updated on Nov 13, 2016.

Common Street Names: K2, Spice, Incense, Fake Weed, Yucatan Fire, Genie, Skunk, Moon Rocks, Zohai, Black Mamba

What is Synthetic Marijuana?

Synthetic marijuana is a designer drug in which herbs, incense or other leafy materials are sprayed with lab-synthesized liquid chemicals to mimic the effect of tetrahydrocannabinol (THC), the psychoactive ingredient in the naturally grown cannabis sativa plant. Synthetic marijuana, also known by the name of “Spice” or “K2” first became available in the U.S. in 2008. It was frequently marketed as an incense in colorful three ounce pouches and labeled “not for human consumption”. Spice or K2 became increasingly popular with high school students and young adults because it was legally obtainable from convenience stores, smoke shops, and online - until July 2012 when a national ban was enacted against the sale of synthetic cannabinoids in the U.S.1

Popular belief is that synthetic marijuana is safe, non-toxic, and elicits a psychoactive (mind-altering) effect similar to regular marijuana. However, case reports and surveys have identified serious toxicities that occur with use of synthetic marijuana, and some users have required emergency room treatment. The chemicals synthesized for the production of synthetic pot can be more potent than natural THC found in marijuana, and may have more dangerous side effects. Little is known of the pharmacological profile of the chemicals or their by-products.

How Does Synthetic Marijuana Work?

Synthetic marijuana is ingested in a similar manner to cannabis, either smoked alone in a joint or other device, such as a pipe or a bong, or rolled into a joint with tobacco or natural marijuana. Synthetic pot may also be baked into foods, such as brownies, or made into tea.

Synthetic marijuana users report experiences similar to those produced by natural marijuana -- elevated mood, relaxation, and altered perception. Often, the effects can be  stronger than those of natural marijuana due to the synthesized chemicals. Some users report psychotic effects like extreme anxiety, paranoia, and hallucinations.1

The cannabinoid compounds found in synthetic marijuana act on the same cell receptors as those affected by the THC in natural marijuana. Identified compounds include HU-210, CP 47,497 and homologues, JWH-018, JWH-073, JWH-398, JWH-250 and oleamide.2 However, some of the synthesized compounds in fake marijuana bind much more strongly to THC receptors than regular marijuana, which can lead to a more powerful, unpredictable or dangerous effect. Some synthesized compounds have been noted to be 100 times more potent than the average THC found in marijuana. In addition, as with many illicit designer drugs, the chemical composition may be unknown and some products may be laced with other toxic chemicals. The stronger binding of the synthetic chemicals to the THC receptor sites in the brain may lead to the extreme anxiety and paranoia that have been reported in some users.

Extent of Synthetic Marijuana Use

In the 2011 Monitoring the the Future, a survey on adolescent drug use, past year use of synthetic marijuana use was second only to use of natural marijuana in high school seniors. Roughly 36 percent of U.S. high school seniors reported past year use of natural marijuana, while over 11 percent reported use of synthetic marijuana. However, in 2013, past-year use of synthetic marijuana among high school seniors sharply decreased, from 11.3% in 2012 to 7.9%. Interestingly, when surveyed about the use of natural marijuana, trends (2008 to 2013) showed that past-month use increased from 5.8% to 7.0% among 8th graders, 13.8% to 18.0% among 10th graders, and from 19.4% to 22.7% among 12th graders. These increases continue to parallel softening attitudes about the perceived risk of harm and disapproval associated with marijuana use.

While the chemicals sprayed on plant material to produce synthetic marijuana were previously not easily detectable in standard drug tests, that is changing and some drug tests now include assays to identify five common compounds found in synthetic marijuana.1

The chemicals used in synthetic marijuana have a high potential for abuse and no medical benefit. The Drug Enforcement Administration (DEA) has designated many active chemicals most frequently found in synthetic marijuana as Schedule I controlled substances, making it illegal to sell, buy, or possess them. Manufacturers of synthetic marijuana products attempt to evade these legal restrictions by substituting different chemicals in their mixtures, while the DEA continues to monitor the situation and evaluate the need for updating the list of banned cannabinoid derivatives.1

Synthetic Marijuana Health Hazards and Addiction Potential

The 2012 DAWN Report from the U.S. Substance Abuse and Mental Health Services Administration (SAMHSA) states that toxicity due to synthetic marijuana resulted in 11,400 cases of emergency room visits in 2010. Complications due to synthetic pot use include high blood pressure, nausea, vomiting, anxiety, agitation and seizures.

Synthetic marijuana abusers who have been taken to Poison Control Centers report symptoms that include rapid heart rate, vomiting, agitation, profuse sweating, confusion, and hallucinations Spice/K2 can also raise blood pressure and cause reduced blood supply to the heart (myocardial ischemia), and in a few cases it has been associated with heart attacks.1

Published case reports in a 2011 edition of Pediatrics describe three teenagers who were hospitalized after using Spice/K2. The patients demonstrated varying degrees of catatonia (an inability to respond to verbal or physical stimulation - including pain) an elevated heart rate, agitation, anxiety, dizziness, headaches, excessive sweating, slowed speech, and confusion. Two of the patients recovered to normal function in three to four hours, while the third patient was kept in hospital overnight before being released.3,4

The long-term effects of synthetic marijuana on reproduction, cancer development, memory or addiction potential are not known. One report suggests some of these products may contain heavy metal residues that may be harmful to health. Other reports claim synthetic marijuana can be addicting -- users who have had even unpleasant experiences crave additional drug. Regular users may experience withdrawal  symptoms.

Cannabimimetics [e.g. “Spice” (containing JWH018, JWH073), HU-210] are prohibited in certain competitive sports and can be found on the World Anti-Doping List. Laboratory tests are becoming increasingly common for the detection of Spice/K2 in urine drug screens. Like marijuana, the active ingredients in Spice/K2 can be stored in the body for long periods of time.5


See Also


  1. DrugFacts: Spice (Synthetic Marijuana). National Institute on Drug Abuse (NIDA): Updated May 2012. Accessed Nov. 13, 2016.
  2. Understanding the ‘Spice’ Phenomenon. European Monitoring Centre for Drugs and Drug Addiction. Accessed Nov. 13, 2016.—%20final%20version.pdf
  3. Cohen, J., Morrison, S., Greenberg, J., & Saidinejad, M. (2012). Clinical Presentation of Intoxication Due to Synthetic Cannabinoids. Pediatrics, 129(4), e1064-e1067.
  4. Haiken M. “Spice” and “K2” vs. “Bath Salts”: The Other Designer Drug Scare. Forbes 6/13/2012.
  5. Johnston, L. D., O'Malley, P. M., Bachman, J. G., & Schulenberg, J. E. "American teens more cautious about using synthetic drugs." University of Michigan News Service: Ann Arbor, MI. Accessed Nov. 13, 2016 at

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