Synthetic Cannabinoids (Synthetic Marijuana, Spice, K2)
Common Street Names: K2, Spice, AK47, Incense, Fake Weed, Yucatan Fire, Genie, Skunk, Moon Rocks, Zohai, Black Mamba
What is synthetic marijuana (synthetic cannabinoids, K2 or Spice)?
Synthetic cannabinoids, also known commonly by the name of “Spice” or “K2”, first became available in the U.S. in the mid-2000’s. These synthetic products are designer drugs in which incense or other leafy materials are sprayed with lab-synthesized liquid chemicals to mimic (copy) the effect of tetrahydrocannabinol (THC), the psychoactive ingredient in the naturally grown cannabis sativa plant.
Synthetic cannabinoids are sometimes incorrectly called “synthetic marijuana” (or “fake weed”), and they are often promoted as safe or legal substitutes to natural marijuana. There is no actual marijuana plant in synthetic cannabinoids; however, the action of the chemicals still take affect on the cannabinoid (THC) receptors in the brain. Synthetic cannabinoids can produce very different actions from smoking natural marijuana. The effects can be much more intense, unpleasant and sometimes dangerous compared to naturally-grown marijuana.
Is synthetic cannabinoids (“synthetic marijuana”) still available in stores?
Spice or K2 has been marketed as an incense in colorful three ounce pouches or vials and labeled “not for human consumption”. Spice or K2 became increasingly popular with high school students and young adults in the mid-2000’s because it was legal and easily obtainable from convenience stores, smoke shops, and online. However, in July 2012 a national ban was enacted against the sale of synthetic cannabinoids in the U.S. 1 Local and state laws also regulate synthetic cannabinoids. While synthetic cannabinoids are illegal in the U.S., the product may still be found sold illegally on the streets.
Popular belief is that “Spice” or “K2” is safe, non-toxic, and results in a psychoactive (mind-altering) effect similar to regular marijuana. However, case reports and surveys have identified serious toxicities that occur with use of synthetic cannabinoids, and some users have required emergency room treatment. The chemicals synthesized for the production of synthetic cannabinoids can be more potent than natural THC found in natural marijuana, and may have more dangerous side effects. Little is known of the pharmacological profile of the chemicals or their by-products.
How are synthetic cannabinoids used?
Synthetic cannabinoids are ingested in a similar manner to marijuana, 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. This product may also be baked into foods, such as brownies, or made into tea.
Synthetic cannabinoid 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 Emergency department visits due to the effects of synthetic cannabinoid ingestion have been reported.
What chemicals are in Spice or K2?
The cannabinoid compounds found in these synthetic agents act on the same cell receptors as those affected by the THC in natural marijuana. Identified compounds include 2 :
- CP 47,497 and homologues
Some of the synthesized compounds in “fake pot” bind much more strongly to THC receptors than regular marijuana, which can lead to more powerful, unpredictable or dangerous effects. Synthesized compounds have been noted to be 100 times more potent than the average THC found in marijuana. 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.
In addition, as with many illicit designer drugs, the chemical composition may be unknown and some products may be combined with other toxic chemicals. In 2018, reports surfaced of synthetic cannabinoids being laced with fentanyl in Connecticut, as reported by NPR.
The chemicals used in these products have a high potential for abuse and no medical benefit. The Drug Enforcement Administration (DEA) has designated many active chemicals found most frequently in synthetic cannabinoids as Schedule I controlled substances, the most restrictive schedule, making it illegal to sell, buy, or possess them. Manufacturers attempt to evade these legal restrictions by substituting different chemicals in their mixtures, while the DEA continues to monitor and update the list of banned cannabinoid derivatives. 1
Are synthetic cannabinoids (synthetic marijuana) dangerous?
Yes, synthetic cannabinoids can be dangerous, as described in several case reports and alerts from U.S. health care authorities. Complications due to synthetic pot use may include:
- high blood pressure
- nausea and vomiting
- anxiety or agitation
- rapid heart rate (tachycardia)
- excessive sweating
Spice and 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 Pediatrics describe three teenagers who were hospitalized after using synthetic cannabinoids. These 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
Synthetic cannabinoids and bleeding risk
In mid-March 2018, the Illinois Department of Heath reported several cases of severe bleeding in people who had used synthetic cannabinoids, such as Spice or K2, contaminated with blood thinners. Subsequently, the Centers for Disease Control and Prevention (CDC) posted an Outbreak Alert warning of life-threatening vitamin K-dependent antagonist bleeding disorders linked with synthetic cannabinoid use in Illinois and other states. Four deaths due to severe bleeding were reported in Illinois. 5
Laboratory testing confirmed that patients were exposed to brodifacoum (an anticoagulant, or blood thinner in rat poison) due to contaminated synthetic cannabinoids. 6 In reports since this time, other anticoagulants have been identified in these synthetic products. 5 Symptoms that can be expected with ingestion of synthetic cannabinoids laced with anticoagulant rat poison or other blood thinners can include:
- excessive bleeding
- bleeding gums
- coughing up or vomiting blood
- pink or red urine due to blood in urine
- dark-colored stools or blood in stools
- excessively heavy menstrual bleeding
- back or stomach pain
- loss of consciousness
If you have consumed synthetic marijuana and have signs or symptoms of bleeding, call 911 or go to an emergency room immediately, tell the doctor you have smoked synthetic marijuana and that you are bleeding, or may be bleeding. Laboratory tests can determine the extent of your anticoagulation and long-term vitamin K (phytonadione) treatment may be started to reverse the effects of the blood thinner. 7,8 This is a serious and life-threatening situation. Do not delay treatment.
There have been reports that Spice or K2 may be laced with other illicit substances, such as fentanyl, which can rapidly lead to respiratory depression and death. Synthetic cannabinoids are created illegally, are not regulated by any authority and may be contaminated with any number of poisonous substances.
Long-term effects of synthetic cannabinoid use
The long-term effects of synthetic cannabinoids 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.
Extent of synthetic marijuana use in teens
In the 2018 Monitoring the Future Survey, a survey from the National Institute of Drug Abuse (NIDA) on adolescent drug use, past year use of synthetic marijuana use was second only to use of natural marijuana in high school seniors. However, in general, rates of Spice or K2 use have remained low among teens in the U.S.
- Roughly 36% of U.S. high school seniors reported past year use of natural marijuana, while 3.5% reported use of synthetic cannabinoids.
- In fact, rates of synthetic marijuana use have been declining since 2012 when it was at its highest; in 2012, 11.3% of high school seniors reported use of Spice or K2.
- These numbers are not surprising considering the increased legal status of recreation marijuana in the U.S., and the continued illegal classification of synthetic cannabinoids.
Do drug tests screen for Spice or K2?
While the chemicals sprayed on plant material to produce Spice or K2 were previously not easily detectable in standard drug tests, that is changing and some drug tests now include assays to identify the common compounds found in synthetic marijuana. 1
Cannabimimetics (for example, “Spice” or “K2” containing JWH018, JWH073, HU-210, and other analogs) 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 and K2 in urine drug screens. Like marijuana, the active ingredients in Spice and K2 have a long half-life and can be stored in the body for extended periods of time. 8
- Drug Testing FAQs
- Marijuana Overview
- Illicit Drug Use and Alcohol Interactions
- Bath Salts
- Devil’s Breath
- Fentanyl (Abuse)
- Gray Death
- Hashish (Hash)
- MDMA (Ecstasy, Molly)
- Mescaline (Peyote)
- PCP (Phencyclidine)
- Psilocybin (Magic Mushrooms)
- Speed (methamphetamine)
- TCP (Tenocyclidine)
- U-47700 (Pink)
- DrugFacts: Spice (Synthetic Marijuana). National Institute on Drug Abuse (NIDA): Updated May 2012. Accessed June 13, 2019. https://www.drugabuse.gov/publications/drugfacts/synthetic-cannabinoids-k2spice
- Understanding the ‘Spice’ Phenomenon. European Monitoring Centre for Drugs and Drug Addiction. Accessed June 13, 2019 at http://www.emcdda.europa.eu/attachements.cfm/att_80086_EN_Spice%20Thematic%20paper%20—%20final%20version.pdf
- Cohen J, Morrison S., Greenberg J., et al. Clinical Presentation of Intoxication Due to Synthetic Cannabinoids. Pediatrics. 2012:129(4), e1064-e1067.
Haiken M. “Spice” and “K2” vs. “Bath Salts”: The Other Designer Drug Scare. Forbes. June 2012.
US Centers for Disease Control and Prevention (CDC). Outbreak Alert: Potential Life-Threatening Vitamin K-Dependent Antagonist Coagulopathy Associated With Synthetic Cannabinoids Use. April 5, 2018.
Rat Poison in Synthetic Pot Can Kill Users: Report. Sept. 26, 2018. Drugs.com Consumer News. Accessed June 13, 2019 at https://www.drugs.com/news/rat-poison-synthetic-pot-can-kill-users-report-77329.html
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Synthetic cannabinoid (often called synthetic marijuana) is a man-made drug of lab-synthesized chemicals sprayed on to leafy material to mimic the effect of tetrahydrocannabinol (THC), the psychoactive ingredient found naturally in marijuana (cannabis).
Synthetic Cannabinoids (K2/Spice) DrugFacts
What are synthetic cannabinoids?
Synthetic cannabinoids are human-made mind-altering chemicals that are either sprayed on dried, shredded plant material so they can be smoked or sold as liquids to be vaporized and inhaled in e-cigarettes and other devices. These products are also known as herbal or liquid incense.
These chemicals are called cannabinoids because they are similar to chemicals found in the marijuana plant. Because of this similarity, synthetic cannabinoids are sometimes misleadingly called synthetic marijuana (or fake weed), and they are often marketed as safe, legal alternatives to that drug. In fact, they are not safe and may affect the brain much more powerfully than marijuana; their actual effects can be unpredictable and, in some cases, more dangerous or even life-threatening.
Synthetic cannabinoids are part of a group of drugs called new psychoactive substances (NPS). NPS are unregulated mind-altering substances that have become newly available on the market and are intended to produce the same effects as illegal drugs. Some of these substances may have been around for years but have reentered the market in altered chemical forms, or due to renewed popularity.
Synthetic cannabinoid products are often labeled “not for human consumption.” Labels also often claim that they contain natural material taken from a variety of plants. However, the only parts of these products that are natural are the dried plant materials. Chemical tests show that the active, mind-altering ingredients are cannabinoid compounds made in laboratories.
Manufacturers sell these products in colorful foil packages and plastic bottles to attract consumers. They market these products under a wide variety of specific brand names. Hundreds of brands now exist, including K2, Spice, Joker, Black Mamba, Kush, and Kronic.
For several years, synthetic cannabinoid mixtures have been easy to buy in drug paraphernalia shops, novelty stores, gas stations, and over the internet. Because the chemicals used in them have no medical benefit and a high potential for abuse, authorities have made it illegal to sell, buy, or possess some of these chemicals. However, manufacturers try to sidestep these laws by changing the chemical formulas in their mixtures.
Easy access and the belief that synthetic cannabinoid products are natural and therefore harmless, have likely contributed to their use among young people. Another reason for their continued use is that standard drug tests cannot easily detect many of the chemicals used in these products.
How do people use synthetic cannabinoids?
The most common way to use synthetic cannabinoids is to smoke the dried plant material. Users also mix the sprayed plant material with marijuana or brew it as tea. Other users buy synthetic cannabinoid products as liquids to vaporize in e-cigarettes.
How do synthetic cannabinoids affect the brain?
Synthetic cannabinoids act on the same brain cell receptors as THC (delta-9-tetrahydrocannabinol), the mind-altering ingredient in marijuana.
So far, there have been few scientific studies of the effects of synthetic cannabinoids on the human brain, but researchers do know that some of them bind more strongly than marijuana to the cell receptors affected by THC and can produce much stronger effects. The resulting health effects can be unpredictable and dangerous.
Because the chemical composition of many synthetic cannabinoid products is unknown and may change from batch to batch, these products are likely to contain substances that cause dramatically different effects than the user might expect.
Synthetic cannabinoid users report some effects similar to those produced by marijuana:
- elevated mood
- altered perception—awareness of surrounding objects and conditions
- symptoms of psychosis—delusional or disordered thinking detached from reality
Psychotic effects include:
- extreme anxiety
- paranoia—extreme and unreasonable distrust of others
- hallucinations—sensations and images that seem real though they are not
What are some other health effects of synthetic cannabinoids?
People who have used synthetic cannabinoids and have been taken to emergency rooms have shown severe effects including:
- rapid heart rate
- violent behavior
- suicidal thoughts
Are synthetic cannabinoids addictive?
Yes, synthetic cannabinoids can be addictive. Regular users trying to quit may have the following withdrawal symptoms:
Behavioral therapies and medications have not specifically been tested for treatment of addiction to these products. Health care providers should screen patients for possible co-occurring mental health conditions.
Can you overdose on synthetic cannabinoids?
Yes. An overdose occurs when a person uses too much of a drug and has a dangerous reaction that results in serious, harmful symptoms or death. Use of synthetic cannabinoids can cause:
- toxic reactions
- elevated blood pressure
- reduced blood supply to the heart
- kidney damage
Deaths can also occur when dangerous synthetic opioids, such as fentanyl, are added to the packaged mixture without the user knowing it.
Points to Remember
- Synthetic cannabinoids refer to a growing number of human-made mind-altering chemicals sprayed on dried, shredded plant material or vaporized to produce a high.
- Synthetic cannabinoids are sometimes misleadingly called synthetic marijuana (or fake weed) because they act on the same brain cell receptors as THC, the mind-altering ingredient in marijuana.
- The effects of synthetic cannabinoids can be unpredictable and severe or even life-threatening.
- The only parts of synthetic cannabinoid products that are natural are the dried plant materials. Chemical tests show that their active ingredients are human-made cannabinoid compounds.
- Synthetic cannabinoid users report some effects similar to those produced by marijuana:
- elevated mood
- altered perception
- symptoms of psychosis
- Synthetic cannabinoids can also cause serious mental and physical health problems including:
- rapid heart rate
- violent behavior
- suicidal thoughts
- Synthetic cannabinoids can be addictive.
- Behavioral therapies and medications have not specifically been tested for treatment of addiction to these products.
- Overdoses can occur and can cause:
- toxic reactions
- raised blood pressure
- reduced blood supply to the heart
- kidney damage
- Deaths can occur when dangerous synthetic opioids, such as fentanyl, are added without the user knowing.
For additional information about synthetic cannabinoids, visit:
- NIDA for Teens Drug Facts on Spice – Offers resources for teens and teen influencers. Get the latest on how drugs affect the brain and body. Features videos, games, blog posts, and more!
- Easy-to-Read Drug Facts on Spice (K2) – Has pictures and videos to help readers understand the text. The website also can read each page out loud.
A plain language summary of synthetic cannabinoids, how they are used, and how they affect the brain and body.