How does K2 work?

K2 works by affecting the brain and mimicking the effects of marijuana on the body. More on K2’s uses, side effects, and dangers here.

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K2 is made of illicit drugs and chemicals meant to mimic the effects of THC, the psychoactive ingredient of marijuana.

The length of time K2 stays in the system varies by person, although most effects wear off within a few days and K2 metabolites are detected up to 72 hours after ingestion.  So how does K2 affect the body and brain? Does K2 have the same effects for everyone? What are the dangers and side effects of K2 use? Finally, is K2 addictive? We’ll explore all those questions and more here, and we welcome your questions about how K2 works at the end.

How does K2 work in the body?

Since K2 is a very new drug in the U.S., it’s not completely clear to researchers, scientists and pharmacology experts exactly how K2 ingredients work in the body. Plus, no two packs of K2 Spice are really the same. In fact, there are currently over 100 types of synthetic cannabinoids on the market. So what’s in K2?

Packets of K2 contain shredded plants which have been sprayed with chemical compounds meant to mimic the “high” of marijuana. Each individual batch of K2 might contain different chemicals or combinations of chemicals (not to mention different types of plants), so it may have very different effects each time it’s taken.  Some of the most common chemicals found in K2 include:

  • AM – 694
  • CP – 47,497
  • CP – 47,497-C8
  • HU-210
  • JWH – 015
  • JWH – 018
  • JWH – 019
  • JWH – 073
  • JWH – 122
  • JWH – 200
  • JWH – 250
  • JWH – 398

How does K2 affect the brain and nervous system?

In general, K2’s side effects are reported to be very unpleasant, and can sometimes be very dangerous. Emergency departments across the US are seeing a rise in K2-related visits, leading to crackdowns on what’s been marketed as a “legal” high. Even if you don’t overdose on K2, the effect on the heart and the brain can be disturbing. In fact, many more people are reporting hallucinations and bad trips on K2, or becoming addicted to K2 incense. K2 affects the central nervous system and can cause a variety of effects, including:

  • agitation
  • hallucinations
  • rapid heart rate
  • vomiting

How fast does K2 work?

K2 enters the body quickly when smoked, with effects beginning within 5-10 minutes of taking the drug. The synthetic cannabinoids contained in K2 reach peak levels in the blood within 10-45 minutes. However, it’s currently unclear how long K2 stays in the body after being taken, although special urine based drug screens can detect K2 use within 2-3 days of ingestion.

How long does K2 work?

K2’s effects start to drop off within 45 minutes. However, the half-life of synthetic weed like K2 is often slightly longer than that of THC, creating a longer-lasting high than marijuana.

What makes K2 work better

K2 is most often smoked, sometimes alone in a pipe, and sometimes mixed with tobacco in a cigarette. Often, it’s labeled as “incense” and marked “not for human consumption.” Given the variety of potential side effects, people interested in trying K2 might want to take that warning to heart. K2 is also sometimes taken as a tea after being steeped in warm water, which will have a slower and milder onset of effects.

Does K2 work for everyone?

K2 is a risky alternative to marijuana, although some people seem to take K2 without the side effects. So little is known about K2, and this can be much more dangerous than taking a drug with more research behind it.

Furthermore, K2 is still sometimes marketed as a “legal” alternative to marijuana, but this is no longer true – many states and the U.S. military have made the drug illegal, and there are current federal restrictions on its use. While some people recommend taking K2 to avoid a positive drug test, it’s not a foolproof strategy. New drug tests are increasingly looking for the synthetic cannabinoids found in K2 and similar products.

How K2 works questions

Do you still have questions about K2? Please leave your questions or comment below. We invite your discussion about K2 and will try to respond to all queries with a personal and prompt reply.

Reference Sources: National Institute on Drug Abuse: InfoFacts: Spice
Drug Enforcement Agency: Drug Fact Sheet: K2 or Spice
NIDA for Teens: “Spice” – Not as fun as it sounds
About the author
Lee Weber is a published author, medical writer, and woman in long-term recovery from addiction. Her latest book, The Definitive Guide to Addiction Interventions is set to reach university bookstores in early 2019.


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  1. I was just on k2 or “legal” not even that long ago. All I can say is that this drug is something that you do not want to be around. You will have the most absolute horrible time in your life and it is not at all worth your time or worth you possibly dying. I was at a point where I felt trapped and thought I would never get out, but I somehow manage to get in control and sober up. This drug is not worth anything at all! Please stay away from it!!!

  2. We have been having a large amount of k2 issues with our work site. We have been finding people becoming nauseous and with sky rocketed blood pressure, when they come in contact with a strong sweet odor. People I have talked to state that k2 doesn’t cause these effects but my question is, can k2 be mixed with other chemicals to create a knock out effect?

    1. Hi Tofs. There are 5 primary chemicals used in K2: JWH-018; JWH-073, JWH-200, CP-47,497, and cannabicyclohexanol. However, it’s not easy to determine exactly what is in Spice/K2. There are currently over 140 synthetic cannabinoids on the market. Keep in mind that K2/ Spice is an unregulated mixture of any of these different compounds.

  3. i have not had any bad tripps ever and have been smoking it since 2007 when it was first introduced to the streets my memory does go from time to time though it al depends on the individual i guess..

  4. Apparently everyone is fucking stupid, because, as the story goes, you oversmoke it
    If you oversmoke it you are the dumbass, aww you love that you cant oversmoke marijuana
    We have other types of cutoffs and caps too maybe you should not hold a job

    This goes for everyone overdosing on spice: stop overdoing on spice. Spice can be the alternative to your heorin, crack cocaine, alcohol, or marijuana addiction. But you can only smoke “2-3 ‘specks’ of this shit”.

    So would you bastards stop being so fucking drugaddict and stop suiciding for the country?

  5. My nephew is bipolar and he smokes k2 in the house periodcally. When i’m sleep in my room i can smell the stuff coming through the vent in my room. Can k2 cause nose bleeds and headaches when inhaled as second hand smoke coming from another room in the house and not direct contact?

    1. Hi Linda. Medical and science experts are still looking into the effects of synthetic cannabinoids. It’s a relatively new drug and not all effects are known. I am not aware of any qualitative studies done so far that explore the second hand side effects of K2/Spice smoke.

  6. My son smokes k2 everyday,sometimes he got to go to the hospital, because he be in so much long can a person keep smoking that stuff.before something bad happens.

  7. I’m glad I read this, I was putting some serious thought into trying it. Now I’m not going to. It sounds like bath salts masquerading as legal weed.

  8. Ok I’m in the 10 grade and these kids were thinking about smoking spice or k2 on my bus and I was concerned that i will get second hand high just by the smell is this true

  9. Been addicted to this for three years. I can’t stop because I commit so much that I lose my voice. At 33 as a woman who has perfect teeth never a cavity now I vomit from withdrawals so much I just can’t get through it to come out on the other end. I started having series the months ago and have had six or seven now. I’m sure this is going to kill me. Don’t try it you will be sorry trust me I sure am and now I’m screwed…Also I have had seizures is what I mean not series.

  10. I took a small pinch of k2, and time it on my watch, within 3 mins it hits you hard. You’re heart rate shoots straight up, don’t panic, cause it feels I like you are dying. After that peak, it’s very euphoric feeling of high and stoned.

  11. I Smoked k2 yesterday I am 14 years old and this is probably the most stupid thing ive ever done… We were on this field and I took alot of hits I got so messed up I couldn’t stop laughing when it started and my friend was like Sam stop your creeping me out I had to hold my breath for me to stop laughing and then a few seconds later that went away then I was so dizzy I could barely walk I could not walk straight at all. I sat down for a while and my friend just kept babbling on about nonsence so we went home I was worse than him so when we got back I went to the bathroom as not to get caught by his parents and I started feeling sick and I think I vomited a whole weeks amount of food.. Jk but it was like real bad vomiting and my senses were going through the roof so I could feel every bone move in my body I could feel my tounge so detailed touching the roof of my tounge and my mouth was so dry we got caught cus I kept getting sick and my pupils were massive…I just want to say k2 is not a joke at all every batch of it is different one can be weakly sprayed and the other could be covered with all the chemicals they put on and everyone reacts different to it so I advising, STAY AWAY FROM it stay with weed something natural, peace and sorry that this was long my heart is still racing today

  12. Hi Kaitlyn. Yes, smoking K2 can cause increased perspiration, but it usually occurs when someone stops using the synthetic marijuana, as a symptom of withdrawal.

  13. k2 doesn’t do shit to me i’ve been smokin’ real tree for years. stick to if fellas Fuck this Shit it only tries to mimic the high.

  14. my life was going great being able to smoke weed, but then my work started drug testing me and I had to stop smoking weed so I switched to spice. Ive been smoking spice for about 2 weeks now and I can say that everything I have read on here has been pretty true. when I first started smoking spice I would take a fat hit and I would sit at a bench for 30-45 minutes like a zombie. I couldn’t talk, stand up or really even think. then I started smoking it more and my tolerance got higher and im able to talk and move around when im high on it. but then about 3 days ago I woke up and went to used the bathroom and I had diareah so bad. I finally got off the toilet and 5 minutes later I was throwing up hard. And that is how ive felt the last 3 days except I havnt thrown up today. I havnt smoked today and im seriously thinking of stoping smoking this stuff cuz of the lack of information known about this drug and my own personal experience of being high on it.

  15. Paul, this drug could indeed raise your levels because it is stressing your system…I am not a doctor but you need to quit using K2. It is in NO WAY a safe drug, smoke pot instead, and if you cannot do that, do nothing.

  16. I would like to know what if any effects the k-2 would have on a diabetic sugar test I have been having my counts reading in the 300s. I am not on insulin. Have type 2. No pills. I manage it with diet and eating right. I am leading my self to k-2 giving me false readings on my meter. Meter is good as well as battery.

  17. Let me tell u I am a nurse and I have seen that saddest case 28 year old came in for smoking k2.she had major strokes which left her to barely walk talk our even feed herself. If u wanna be like this go for it but dont expect pitty from others u did it yourself

  18. Hi James. Yes! Try this search in Google to extract most recent studies, data, and government initiatives. spice cannabinoids +2013..2014

  19. i used to smoke it when it first came out…never had a bad trip. the new stuff i tried a few yrs later with my brothers girlfriend and ended up blacking out 4 times within a couple mins, and my dad had to help me up the steps into my room. I was covered in sweat and it was soaked through my clothing. I said I’d never touch it again, but have smoked a few times since and only had about 3 anxiety/panic attacks, but nothing as serious as blacking out. My friend also had a bad trip the first time, she cldnt stop twitching for 3 days and thought it might be permanent.
    PS: if it helps, i do get like chronic black out spells, just no where near as bad as the time I smoked with my bros girl.
    I guess if ur desperate to get high off of something its a good choice, and alternative to other worse drugs, but otherwise steer clear.

  20. K2 is very dangerous.. I still smoke it.. I gotta quit… bad migraine, more eating, and alot of money… if u haven’t then dont!!!!!!!!

  21. For all the kids on here who think spice, herbal or K2 is not harmful, LISTEN UP:
    It is, and it can cause death by overdose. I have seen it happen, and since the ingredients are always changing in k2,etc, then you are truly clueless to what you are taking. It is not harmless like pot. It is not safe and can cause awful, if not fatal, side effects. To you young people who really think you are okay, better quit now before some ingredient in it kills you.

  22. I smoked k2 2 days ago..i wish I never would have it was a fun trip don’t get me wrong…but now I have a fervor of 105 my stomach hurts so bad I’m shaking like a mad man I left school early today because of it I haven’t been able to sleep please I beg of you don’t do K2 if ur gonna smoke stick to pot

  23. i have done it once or twice then i said i never wanted to do it agine i oeverdos and i was i the hospitel for 3 day then i could not see me family caz i had to go to drug rehabe .. i miss 2 of my lil sister brithday caz i wanted to be cool i do it … But its stupid and it almost killed me amd im olny 15 years old. when i got home and seen my mom and lil sister mad at me i begin to cry caz i missed them soo bad then my mom grab me and was holding me soo tied she said i all most lost my baby . SOO PEOPLE PLZ DONT DO IT IT’S NOT LOSING YOUR LIFE OVER YOU SPECIAL TO SO ONE IN LIFE LIKE I WAS TO MY FAMILY.. THANK YOU MOM & FAMILY

  24. I smoked this stuff twice once the day before yesterday and the other timwas about six months ago.I have a very promising future ahead of me. Now how bad will this stuff effect my brain? Will this affect my intelligence? And I still feel the effect from 2 days ago but just slightly. Is this bad?

  25. I was smoking different kinds of k2 for two years and about a year after smoking, i switched to a spice called bazzaro. That by far was the most potent. i was smoking over 5 grams a day which is a lot of smoke. Towards the end of the second year of smoking k2 i was having bad health problems. i was having rapid heart rate, chest pains and heart pains. i was completely addicted. Bad withdrawls. Iv been off k2 for 4 months now and will never touch that stuff again. im still having heart and chest pains and i know its from smoking that stuff. what common problems are other having, and what does it all effect in the body?

  26. K2 messes u right up my brother in
    Law now believes he is a demi god taking that all the side effects are true if urve been taking that stuf for so long an try go back to marijuana u wouldn’t even get a buzz as k2 is way to powerful

  27. Hi Melissa. Do a Google search for: effects synthetic cannabinoids +”second hand”

    You will find the latest government reports on Spice that your sister can bring to her employer. Second hand smoke is definitely a health and safety issues. Perhaps she can even get in touch with the Occupational Safety and Health Administration to see what kinds of conditions are acceptable and to report what is happening.

  28. What are the second hand effects of this? My sister works in a facility where federal prisoners transition out of the prison system. Prisoners stay there during the evening and go out in the community to work during the day. Used to be if these tenants were found with drugs on them, they were sent back to prison. The Federal Bureau of Prison Systems changed those rules. They cannot be sent back. So she has a dorm full of “tenants” who sneak the stuff in and smoke it all night. The monitors used to have to go in there to count the inmates but they complained loud enough about the smoke and the smell that they no longer have to enter the dorm. However, my sister’s office is below their dorm. She breathes the stuff all day. When she goes home at night, she literally has no voice. I’m afraid she’s getting ill from this exposure. She’s complained to her boss, but as of yet, they’ve done nothing. She has scheduled a doctor’s appointment for herself and said she’s going to start wearing a mask while she’s at work. Is there any information available in this regard? Thanks!

  29. Hi, I saw this looking for answers to my daughters condition. We aren’t sure this is what her condition is, but we are pretty sure it pushed her over the edge.

    My daughter and her husband have been daily pot smokers since they were teenagers. As of last week, she was admitted to a State Mental Hospital. She experienced what the doctors are calling a psychotic break. It was the most awful thing to witness happening to my child. Especially, when she has a 7 year old of her own.

    Apparently, supply was low and sellers kept raising the price of the stuff. As much as 40 dollars I was told. This is significant, due to the timeframe of her condition.

    She seemed to change in only a month and only took 7 days to totally lose it. They were smoking more than they ever had at one time and my daughter seemed to just smoke it all day long. She couldn’t help herself. She started sleeping all day and mumbling under her breath. Talking to no one and staring off into space. Having racing heartbeat and saying it felt like someone was touching her. Hearing voices. Taking a knife to try to kill herself. Until she finally started screaming and went into a seizure in the hospital waiting room.

    She was a perfectly normal person before Thanksgiving. And, you can’t say it wasn’t K-2. 3 other people were smoking the same stuff. All complained of some ailment. Headaches, racing thoughts, inability to focus, more powerful high. They all believe that what they thought was just pot was mixed with K-2. BUYERS BEWARE. Even if you know your suppliers, you don’t know what you’re getting.

    Granted, they think my daughter may have had a problem before the drug, but whatever was in that pot made it break and speed up the process. It may have caused more permanent damage. She’s doing better and she’s lucid again, but the paranoia is still there and she is angry at us for trying to help her. The stuff does not bode well as a mass replacement for what is natural. It is missing all of the key elements to sustain it. Granted, the natural stuff is not for me either, but I have never seen people go totally off the deep end on all natural marijuana. This is a killer drug.

  30. There is a lot of misinformation and fear mongering on this subject. It all boils down to the question of, “Should adults be allowed to decide what is and is not good for them?” K2 relieves my anxiety and relaxes me. I have NEVER had a bad experience with it. Everyone is different. Alcohol makes me feel bad….so I don’t drink. Friends of mine have died, gotten into car wrecks, and lost their license. I still don’t begrudge grown adults their freedom to make their own choices. Bottom line: If it makes you feel bad….DONT DO IT… but don’t insist that other grown adults not be allowed to decide for themselves. Everyone knows that McDonalds is bad for your fat asses, so why not make that illegal?? Let’s also throw the morbidly obese in prison, because the poor things just cant manage to think for themselves.

  31. I’m also skeptical about the health concerns related to herbal incense. I’ve been smoking herbal incense for over a year and I haven’t had any problems. Maybe there is some real danger, and if there is I hope the truth comes out, but for now I’m not ready to believe everything I hear.

  32. Hi, My name is xLeGaLBuD, First off I’ve been smoking 5-10 Grams of K2 everyday for just about 2 years, I have no heath problems. The only side affect I have had was being addicted to it. I am an athlete I run track and wrestle. I’m 17, and I have not noticed any problems in my running or wrestling (such as getting tirred more quickly than usal or lacking will power.) I’ve been the the doctors for anual check up and everything has checkout to be fine. I will admit I’ve had bad trips and have had hallucinations
    But thats why I enjoy it so much, I contuinue to smoke it. I belive either I am lucky or all this K2 hype about it killing people is just the goverment to make it illegal just like marijuana.

  33. I smoked k2 about 3 months ago I only took two hits I’m 14 and I got bight instantly every since then my life has been horrible I have headaches all the time I wake up in the middle of the night with anxiety and I keep getting tingly feelings in my body and I also feel like I’m losing feeling in my body I have been to the doctor and they just keep sayn it’s anxiety but its not helping and I just need help please help!!!!!!!

  34. Drugs are never a way to find reality, the point is to seek freedom from within, no drugs will give you what you want.

    As parents we need to be clear and honest with our kids, we need to be sure that we spend time with them, no work or money in more important that the time we spend with our kids face to face, with clear boundaries and clear expectations.

    Drugs kill brain cells, take away the drive that someone may have , increase the boredom and may create a monster in you.

    No healthy future is secure if people get involved with drugs, sooner than later drug charges will appear, lost of money, no job , no education. No close relationships.

    If you want to change your life, there is always help available . Look for it.

  35. Tell your kids to smoke pot instead of this crap. I experienced no negative effects from spice/k2 or any other crap. In fact i remember me and four friends were each taking a jager bomb and a bong rip of k2 back to back in a circle of death type ritual. I actually ending up blacking out from the jager as we had like 9 shots a piece. But i think the 9 bong rips of spice played a part in the blacking out. All in all a fun night but i’d rather leave the spice outta the equation next time.

  36. My son tried K2 and next morning he fell in the bathroom, when i went to see what happened, noticed his whole left side was paralyzed. Scared us both and he won’t touch it again. Now my soninlaw has started smoking it and it is an addiction like crack, he just can’t get enough. Then throws up the next morning. He may be going to the hospital today because his urine is burning and right side in pain. Geez when do people get enough. This is sickening and breaks my heart.

  37. Hi DJ Hastings. K2 manufacturers are constantly changing and evolving the chemical compounds found in K2 to make fake weed “street legal”. However, many of these second and third generation synthetic cannabinoids have never been used on humans, nor tested for potency. Plus, when the chemicals are sprayed onto plant material, sometimes the spray unevenly covers a batch, leaving some plants heavily covered…and triggering hallucinogenic experiences due to overdose.

  38. This stuff is not a joke.. i smoked 3 small hits last night and was so high i couldn’t feel or talk… my body shut down. we where sitting in a parking lot and i LITERALLY fell out of my car and my friend kept shaking me beating me trying to snap me out of it.. I could hear everything he was saying I was yelling inside but nothing was coming out he said i just looked dead. he was crying and i have battle wounds on my knees and hands. it felt like days went by and felt like i was dying.. i remember EVERYTHING that happened. The more I read these stories the more i get worried as to what is going to happen to me. im not paranoid and im not questioning if this is reality or not. I feel perfectly fine. Im just a little worried as to what is going to happen. Last night was the first and LAST time I ever wanna touch it or see it…. my friend said my heart was beating so fast he could barely tell it was beating…. i could breath fine i just felt like i weighed as heavy as a elephant… i have warned everyone I know. If it wasnt for my friend catching me by my neck and arm i would have broke my neck as i slowly fell out of my car. i dont have a headache or anything… im just preparing for the worst. I sat in my car until the high wore off and drove home and drank about 6 cups of water ate food and took vitamin b12 and C… im guessing doing that as a “detox” saved my life. I had to sleep in my aunts room because i was afraid i would stop breathing while I was sleeping.(Freaked out after reading stories) I dont believe i had a big dose… how ever it scared me so bad im scared to smoke ciggs anymore because thats what we used to smoke it…If it wasnt for my friend i would have move deff died last night… it only lasted maybe a half an hour?? but again it felt like it lasted days… ive smoked spice before and it did NOT do this… if you look on the bottom of the k2 container.. its says “reformulated in june 2012” So my question is… WHAT DID THEY ADD!?!?!?!?

  39. I treated the anxiety with adovan and the memory problems and everything dissappeared after 8 months never touching drugs again

  40. Hi Tyler. Thanks for sharing more about your personal experience with Devils Potpourri and Black Mamba. Did you notice these symptoms that you report improve over time, or slowly go away? Did you do anything to help treat the symptoms?

  41. This drug sped up my heart to 118 beats per sec I didnt hallucinate but everything looked 3d and i felt like i was in a fake world 12 hours laters after smoking 2 containers 1 was black mamba the other devils
    pottpouri from 12:00 pm I had a massive anxiety attacked at 11:00 pm
    I called 911 and pumped with oxygen and given anti anxiety the legal stuff was pleasure high this was a horrible high and the withdrawals and headaches lasted for 8 months

  42. We agree, Andy. And some of the psychotic effects K2 has on the mind have been reported to linger after intoxication for weeks or months after use. Because we know SO LITTLE about K2, we tell people to stay away.

  43. K2 is NOT a safe alternative to marijuana, it has a LOT of synthetic ingredients and some of the more “bad trip” psychoactive ingredients in marijuana and much of this is made UNDERGROUND.

    I tried herbal insence and it felt like it had a slight cocaine like euphoric high and I felt a STRONG urge to reinforce the high. Herbal insences and potpourri mixtures have a WIDE variety of ingredients and even the ingredients are laced with dangerously addictive and psychoactive ingredients.

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