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
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- 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).
What to Know About Synthetic Marijuana (Fake Weed) Use
Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital.
Synthetic cannabinoids, also called synthetic marijuana or fake weed, have been used by many as an alternative to marijuana since products were first introduced in 2002. Despite the fact that these man-made products were created in laboratories to help scientists study the cannabinoid system in the human brain, they often claim to be made of “natural” material from a variety of plants.
Hundreds of synthetic cannabinoids exist and the effects can be unpredictable and even life-threatening.
Also Known As: There are countless fake weed products being sold as herbal smoking blends, legal bud, herbal smoke, marijuana alternatives, fake weed, or herbal buds. This makes it difficult for parents and other adults to identify them. Some of the brand names include Blaze, Blueberry Haze, Dank, Demon Passion Smoke, Genie, Hawaiian Hybrid, K2, Magma, Ninja, Nitro, Ono Budz, Panama Red Ball, Puff, Sativah Herbal Smoke, Skunk, Spice, Ultra Chronic, and Voodoo Spice.
Drug Class: Synthetic marijuana products are classified as new psychoactive substances (NPS), or unregulated mind-altering substances intended to produce the same effects as illegal drugs.
Common Side Effects: Side effects of the drug include elevated mood, relaxation, altered perception, symptoms of psychosis, extreme anxiety, confusion, paranoia, hallucinations, violent behavior, suicidal thoughts, rapid heart rate, raised blood pressure, vomiting, kidney damage, and seizures.
How to Recognize Fake Weed
Synthetic marijuana often contains a mixture of dried leaves from traditional herbal plants. They are various colors, including green, brown, blonde, and red, and often sold in small packets approximately two by three inches. The packets are often colorful foil packs or plastic zip bags. Some online sellers of legal fake weed products do so with disclaimers like “not for human consumption.”
What Does Synthetic Marijuana Do?
Fake weed works on the same brain cell receptors as THC or delta-9-tetrahydrocannabinol (the psychoactive ingredient in marijuana that gets you high). It is typically smoked, brewed in tea, or vaped. Many of these products are legally marketed as “herbal incense” or “potpourri”.
Some people who use herbal buds say that it produces a high similar to that of marijuana, but it doesn’t last as long. Others experience a relaxed feeling, rather than the “head high” that real marijuana produces. Also of note is the “harsh” taste, which people say “makes your throat burn and your lungs ache” long after you smoke.
Since there are no standards for making, packaging, or selling synthetic weed, it’s impossible to know the type and amount of chemicals in each product as well as what the fake weed will do to you.
What the Experts Say
Although they are often marketed as “100% organic herbs,” none of the fake weed products on the market are completely natural. They have all been found to contain various synthetic cannabinoids, or chemicals produced in laboratories.
Originally, fake marijuana products contained a chemical called HU-210, which has a molecular structure very similar to THC. Because HU-210 is listed as a Schedule I controlled substance in the United States, these fake weed products were manufactured and sold only in Europe.
Since then, new synthetic cannabinoid agonists have been created. They are too numerous to list. Some are similar in structure to THC; others are not. Some are classified as controlled substances. By using different synthetic marijuana mixtures, manufacturers are able to continue to legally market their products in the United States when another formulation becomes illegal.
According to the DEA, the majority of these chemical compounds are produced in Asia with no regulations or standards. They are then smuggled into the United States where they are sprinkled onto “plant material,” packaged and ultimately sold in tobacco shops, convenience stores, and the like.
Some of these chemicals are still legal. However, since synthetic marijuana first hit the market, more than 20 of these compounds have become controlled in some way at the federal level. At the same time, they noted that more than 75 additional compounds have been identified but are not currently controlled.
In 2015, the DEA listed 15 varieties of synthetic marijuana as Schedule I controlled substances in the Drugs of Abuse resource guide. This places them in the same federal category as heroin, crack cocaine, and marijuana.
Many people buy into the idea that fake marijuana products are safe since the chemicals are “legal” and contain “natural” ingredients. However, this has proven to be false with multiple cases of severe, unexplained bleeding or bruising, and some deaths. Other reports show an increase in emergency room visits due to rapid heart rate, vomiting, violent behavior, suicidal thoughts, kidney damage, and seizures.
Some of the fake marijuana products sold commercially claim to contain herbs traditionally used for medicinal purposes, including:
- Beach bean (Canavalia maritima)
- Blue Egyptian water lily (nymphaea caerulea)
- Dwarf skullcap (scutellaria nana)
- Indian warrior (pedicularis densiflora)
- Lion’s tail (leonotis leonurus)
- Indian lotus (nelumbo nucifera)
- Honeyweed (leonurus sibiricus)
However, one study revealed that some of the herbal ingredients listed by the manufacturers could not be found in the products.
Beyond the synthetic cannibinoid HU-210, which is used by scientists to identify cannibinoid receptors in the brain and study the effects Δ-9-tetrahydrocannabinol (Δ-9-THC), there are no approved or off-label medical uses for synthetic marijuana.
Common Side Effects
While research is advancing, the effect synthetic marijuana products may have on the human body is largely unknown. To date, few studies have been published testing the effects of the chemicals on users. Within the DEA report, they note overdoses that have caused fatal heart attacks. Similarly, acute kidney injury resulting in hospitalization and dialysis have been connected to these synthetics.
One study compared the level of impairment for drivers who were arrested for intoxicated driving. One group had smoked synthetic cannabinoids and those in the other group were high on marijuana. The study found a significant increase in confusion, disorientation, and incoherence in the synthetic marijuana group. Slurred speech, a side effect not normally associated with natural cannabis use, was also reported among the synthetic cannabinoid users.
Beyond the short-term effects mentioned, an increase in blood pressure, as well as seizures, tremors, and anxiety, have been noted in synthetic marijuana users.
Whether these observed symptoms will have lasting effects, particularly on adolescents and young adult users, is not yet known. Of course, smoking any substance could have negative effects on the lungs.
“The problem with JWH-018 (a synthetic cannabinoid compound) is that absolutely nothing is known regarding its toxicity or metabolites,” says John Huffman, who helped develop the JWH-018 chemical. “Therefore, it is potentially dangerous and should not be used.” JWH-018 is also known as 1-Pentyl-3-(1-naphthyl) indole and is one of the Schedule I controlled substances listed with the DEA.
Recently, a version of synthetic marijuana was laced with rat poison, causing uncontrolled bleeding in hundreds of people and killing several others who ingested the tainted products.
If you or a loved one has used synthetic marijuana and begin experiencing severe, unexplained bleeding or bruising, call 911 or asked a loved one to take you to the hospital immediately. These are all signs of contaminated cannabinoid products.
Signs of Use
If you are a parent of a young adult, it pays to know the behaviors and physical effects of using fake weed. While exhibiting one or two of these signs might not mean that your child is using, they are all strong indicators of drug use and should be taken seriously.
- Burning incense
- Buying or using eye drops
- Possessing dried plants or herbs
- Having rolling papers or vape pens
- Receiving suspicious packages in the mail
- Displaying unusual or secretive behaviors
- Red or irritated eyes
- Pale complexion
- Acting confused
Myths and Common Questions
Perhaps one of the biggest misconceptions about herbal bud is that it is “natural marijuana.” It is not; it is created from any of several hundred man-made synthetic chemicals that are sprayed onto the chopped plant material.
Synthetic marijuana is also far more potent, containing TCH analogs or synthetic cannabinoids that can be up to 600 times more potent than THC found in marijuana. Often, additives, toxic impurities, and other types of drugs are also found in fake weed products.
Tolerance, Dependence, and Withdrawal
Regularly using “fake weed” can result in increased tolerance, or needing more and more of the drug to experience the same high. If you regularly use synthetic cannabinoids, you can also become both physically and psychologically dependent. This means if you stop abruptly, you’ll likely experience withdrawal symptoms.
Since the chemical composition of fake weed is unknown and can change from batch to batch, tolerance, dependence, and withdrawal may also vary.
How Long Does Fake Weed Stay in Your System?
How long synthetic cannabinoids stay in your system depends on several factors, including the type, how it is administered (i.e., inhaled or ingested), amount consumed, and frequency of use. Since these synthetic drugs don’t trigger a positive result on most standard urine drug tests , many people turn to these drugs in an attempt to avoid positive drug screens for employment, rehab, or legal reasons.
Long-term, regular use of synthetic cannabinoids can lead to addiction. If you have a history of mental illness or a substance use disorder, the risk of addiction is even greater.
In addition to building up a tolerance and experiencing symptoms of withdrawal, other signs of synthetic cannabinoid addiction can include:
- You use more than intended, even after telling yourself that you’ll only “take a few hits.”
- You are unable to cut down or stop and have likely failed numerous times at quitting.
- You spend lots of time getting high, often at the expense of spending time with loved ones or doing activities you once enjoyed.
- You continue to use despite any problems with family and friends, employment, or legal troubles.
- You depend on the drug to “relax” or for creativity.
Symptoms of synthetic weed withdrawal can range from mild to severe, depending on how frequent and how long you have been using, and include the following:
- Severe anxiety
How to Get Help
If you suspect that someone you love is using synthetic marijuana, the most important thing you can do is spend time with them, communicate the dangers of fake weed, and watch for any signs of use. While behavioral therapies and medications have yet to be specifically tested for the treatment of synthetic cannabinoid addiction, a health care professional can work with you and your loved one to safely detox from the drug as well as identify and treat any co-occurring mental illness.
In addition to getting a recommendation from a trusted health care professional, the Partnership at DrugFree.org has a helpline and tips so families know what to ask when vetting a rehab.
If you or a loved one are struggling with substance use or addiction, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.
For more mental health resources, see our National Helpline Database.
Learn what experts have to say about synthetic marijuana or "fake weed" as well as common side effects, myths, signs of use, and risk for addiction.