How long does K2 last?

K2 effects can last few hours, but can persist for days or weeks after use. More on the factors that affect the duration of K2 and synthetic cannabinoids here.

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Duration of K2 effects

How long K2 effects last depends on individual factors such as:

  • how much you smoke
  • your weight
  • your height
  • your overall health

Researchers do know that the effects from JWH-018 (a specific ingredient which used the be found inK2 products) usually lasts for 1-2 hours, and the effects of CP 47, and 497-C8 (also synthetic cannabinoids) lasts can last for 5-6 hours. But so much less is known about many of the ingredients found in K2.

More on the duration of K2 effects here, with a section at the end for your questions about the addictiveness of K2 or the dangers of smoking K2.

What is in K2?

K2 is a combination of plant based material sprayed with synthetic cannabinoids that can trigger extremely potent THC-like effects. There are many variations on this drug. While packages are labeled “not for human consumption” or “aromatherapy only”, many people smoke K2 to provoke hallucinatory effects.

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Synthetic cannabinoids can be classified into eight general groups, based on the type of chemical alteration made to the original substance. These include:

  • benzoylindoles
  • cyclohexylphenols
  • naphthoylindoles
  • naphthoylpyrroles
  • naphthylideneindenes
  • naphthylmethylindenes/naphthylmethylindoles
  • phenylacetylindoles
  • tetrahydrocannabinols

K2 effects on the body and brain

K2 users claim that experiences on synthetics are similar to those produced by marijuana, relaxation, elevated mood. However, in many cases, how long K2 stays in your body increases in length and the effects of K2 on the brain are stronger than those of marijuana. Some users report psychological effects such hallucinations, panic attacks, paranoia, and agitation. Some physical symptoms can manifest as dangerously elevated heart rates and blood pressure, increased respiration rates, dilated pupils numbness, very pale skin, and/or vomiting. While little is known about the long term effects of K2 on the body or brain, its acute effects can trigger symptoms that are both frightening and dangerous.

K2 duration of action

K2 is usually smoked via a joint or water pipe, which allows quick absorption of synthetic cannabinoids to the bloodstream. Changes in perception and mood start to occur within minutes after inhalation and can last for hours after use. Because of the complex chemical composition of K2, it is likely that some varieties also contain substances that could cause dramatically different effects of the body.

Symptoms such as tachycardia, increased appetite, or xerostomia (dry mouth) can last up to 6 hours after consumption. Some uncomfortable symptoms like nausea and vomiting can also persist for this amount of time. Severe symptoms of K2 intoxication such as hallucinations, vomiting, or high blood pressure / heart rate should be addressed immediately by medical professionals.

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K2 time in the body

Active substances in synthetic cannabis are metabolized in the liver, and ejected in the urine. While K2 may not be detected on a routine urine drug test, the presence of JWH-018 can be detected up to 2 months on a substance-specific test following a single low dose. In the case of chronic use, the detection window for K2 may be longer.

How long does a K2 high last?

Because of the complexity of this drug, it is hard to precisely estimate the duration of the high effect. According to some studies, the duration of a K2 high can last from 1-8 hours, but users claim that the effects last longer. Research studies have shown that and intense high lasts between 10-30 minutes.

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This high produced by synthetic marijuana can also physically alter areas of the brain that are associated with reward, memory and motivation. The cycle looks like this:

Use Spice or K2.

Start your
recovery today.

Feel good!

Use again!

Continue to use in order to feel good!

In fact – this is addiction. And, as regular dosing of K2 progresses, people who experience euphoric effect are on a risky path towards becoming addicted. Luckily, help is available! We outline more about what addiction is and effective treatment options in this guide on Treatment Programs and Help for Spice and K2 Addiction.

K2 high effects

A K2 high effect is similar to that caused by marijuana – relaxation, elevated mood, and altered perception. The difference between them is that the effect of this synthetic drug is stronger. Additionally, because K2 is a combination of new synthetic cannabinoids recently put on the market, experts are not familiar with how it affects the brain. Because we don’t know all the ways K2 may affect a user’s health, or how toxic it may be, use of K2 is highly discouraged.

Questions about K2

Do you have additional questions about K2? Please leave us your questions in the comments section below. We’ll do our best to respond to you personally and promptly…or to refer you to experts who can help.

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Call us today. You don’t need to face addiction on your own.
Reference Sources: National Institute on Drug Abuse: Monitoring the Future. National Results on Adolescent Drug Use
National Institute on Drug Abuse: Drug Facts: Spice (“Synthetic Marijuana”)
Drug Facts: What Is Spice
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. So my girlfriend took a couple hits from a Dab/wax pen and it appears to have been k2/spice. She has had EXTREME anxiety and panic attacks for the past few weeks. She has gone on anxiety medicine and it’s not helping too much. She thinks she’s dead/dying and she has a hard time believing anyone about what’s going on. Me and everyone else are really worried, if anyone has any tips or experiences with this please email me!

  2. this last week I had eaten some cookies that were available in our break room, I got hit heavy with them as they were said to be laced with Pot after a trip to the hospital. a friend of mine suspects it was K2, my question is can K2 be baked into goods like cookies or brownies like pot?

  3. My husband smoked k2 for 2 yes . It was all good ,(we thought) my husband was a tuck driver and one day he started having panic attacks thinking he was going to end up killing someone it was so bad he’d say he tast metal next thing I knew he was on the floor .long story short , he hasn’t worked since , has anger problems ,
    One day my husband nutted up , walked through a glass door shattering the glass , he never new it, that was 2014
    Here it is 2017 and he still has anger problems
    Memory issues all of it , my question is, will he ever be the same as he was ?

  4. I was smoking weed for months but a week and half ago I think I got weed laced with k2 and I want to know the quickest way to get it out and when does these heart rate stop Help

  5. Late Sunday/ early Monday I took a hit from some kids that I recognized from school (not well enough to know their names) I assumed what I smoked was normal weed. This was obviously not the case. I only took one hit and not too long after I was tripping hard. I’m a pretty small person at 5″2 but usually one hit of weed does nothing for me. When I was high everything around me was almost vibrating and nothing seemed real, like I was in a dream, my heart beat was really fast, I was thirsty, I was scared the whole time but at one point I was REALLY nervous and started grabbing my friends arm really hard, fell to the ground, and kept saying ‘I’m too high, it was laced, am I going to die?’ (Luckily my friends were sober) i also felt kinda nauseous but never vomited. The next day I felt ‘numb’ physically and emotionally, I couldn’t feel heat or pain at all, and I wasn’t really anxious or anything (I kinda just didn’t care). Even the day after that I was still emotionally numb. Today I had terrible anxiety, my heart was racing, ex… It’s kinda freaking me out how I don’t know what I did… and I was just wondering if anyone knows if it was K2??

    I also forgot to mention that the high lasted pretty long (at least 4 hours maybe even 6) before i could fully grasp reality. I didn’t get much sleep either.

    1. Hi Valerie. Could be that it was synthetic weed, but it also might have been regular marijuana laced with another drug…can’t really tell for sure. Please see a doctor if the unusual symptoms persist or if you continue to feel unwell.

  6. 5 hours ago ,a friend advised me to try something similar to weed and hash,something I have never tried before after he rolled a cigarette, I only took one puff and through it away, then I realized that it was Spice drug (k2) , that one puff made me extremely high in seconds, and lasted more than 30 minutes after, I was extremely scared, and felt that i’m about to die, and now I’m just feeling mild headache and no paranoia or hallucination happened to me, now i’m asking does only one puff can make chronic illness, do anything should I worry about ?? is that drug can make any physiologic or mental change from only one-puff ??

  7. We went through hell with my 24 yr old son last year and I’d just like to share our experience with K2. My son believed he was sharing a regular joint that a “friend” offered…sadly, it was K2. Long story short, He was brought to the ER with hallucinations, paranoia, extreme panic attacks, he had to leave work for about 6 weeks–he had to stay back home with us while we tried to get him help. There is nothing as terrifying and heartbreaking as having your 24 yr old son (who is a big guy–weightlifter) come to the side of your bed in the middle of the night asking me to stay in bed with him because he is afraid he is going to die during the night. Very luckily, we got him into counseling, got him on some meds for the paranoia. After about 6 weeks he was feeling strong enough to get back to work and his own apartment (3 hours away from us–it was extremely hard for me to let him go back—my husband and I were a wreck). He continued with counseling and meds in his city and now has been weaned of meds and no longer sees a counselor. He is absolutely thriving. I would beg anyone not to try this dangerous drug and to stay away from pot altogether….do you REALLY know what you are smoking? I just pray that any of you that have been affected by this to have as good an outcome as we did. This was a horror story for us, I know others have had much worse experiences.

  8. I was sold what i thought was marijuana, but i found out the hard way that it was K2. i have chest pains, which I spentt two days in the hospital ruling out an MI. I get exhausted very easily with little activity. My stools have a very foul smell. I have convulsions/seizures, some of them being violent. I havent smoked since i found out what it was. I thought IO was dying, so I had my wife call 911. As soon as the EMT came in the room, he knew what it was. That was about 4-5 days ago. How long can I expect these symptoms to occur? Thanks so much for your help!

  9. Hey there. My boyfriend and smoked k2 on monday and for me it felt like weed. He is still feeling effects of the drug and its been 42 hours. He has slight motor paraylis and can barely get out of bed. He says his brain is “cloudy” or feels like “pressure” but he gets better as the days pass. Idk he is a different person since. I am freaked out. Please help!

  10. i snoke k2 for about 2-3 weeks. I already and have depression and anixety and am nocompliant in taking meds. My last hit was abot 8-10 days ago. I am sitll having slight t major panic attacks. cant eat or sleep with out the valume the doc gave me. Slowly thats not working anymore. Every one around says that this should have subsided. But it has not. I will be fine and then an attack. I dont have the craving to use again. which is a good thing. Has any study shown permenant damage.

  11. So it’s been a year since I quit the k2. I’m feeling much better. I do admit to smokjing weed occasionally now but weed is nothing in comparison. I’m healthy and in control of my life. I write this for those that ask “will this high last forever?” Or “will I really be able to quit?” Yes you can and you don’t need rehab to do it, just self control. It’s unfortunate that in a year no one responded to my lenghty original post, but I still get notified if someone adds something to this thread. I wish all those that are still affected by k2 the best in life.

  12. Hi, my name is Zuri my brother was in college and some students gave him k2 instead of marijuana. He was having hallucinations of my dead aunt but he’s gotten better. But he’s now starting to have sweaty palms and he gets nervous easily. How long does the sweaty palms last for and the nervousness?

    1. Hi Zuri. The duration of Spice withdrawal symptoms depend upon how long a person has been abusing the drug, how heavily they were using it and also their predisposition to addiction and psychoses. Generally, symptoms occur in the first hours after a missed dose and can last for days or weeks.

  13. Please i am so scared, i smoked k2 yeasterday and i still kinda feeling it tho i am not high. Please tell me is going to last forever or just temporary?.

  14. I smoked k2 for the first time about 4 or 5 days ago. Not knowing it was k2, I smoked a lot of it. I had a seizure from the panic attacks. I went to the hospital the a night after and they put me on an IV. The hallucinations have stopped but 5 days later and im having extreme headaches and my whole body feels numb. I have no idea why. I don’t know if its going to go away or not and I am very scared that I might feel like this forever.

  15. we believe my son was given K2 instead of marijuana by a “friend”. He smoked it with this person 11 days ago and is having a very rough time with paranoia, anxiety and some delusions. We are scared to death for him and are trying to find out how long he may be feeling like this.

    1. Hi Gina. It depends on the blend of synthetic marijuana and the amount he smoked. In any case, he will be feeling better as he continues not to smoke and his organism heals, but don’t hesitate to seek medical treatment for the effects he is experiencing. I cannot tell how long the effects will persist, though.

    1. Hello Adam. The length of time K2 withdrawal symptoms last depend upon the dosage, and duration of abusing the drug, as well as person’s predisposition to psychoses and addiction. Generally speaking, symptoms occur in the first hours after a missed dose and can last for days or weeks. But, if your situation gets worse, then seek help from a doctor.

  16. hello my son started smoking this crap to replace pot cause of a union job. he says he stopped smoking it 3 days ago. but, i still feel unsettled. he is not having withdrawals thats why i can’t understand. but i check his eyes and speech and no dilate normal pupils and speech is clearer. can u tell me otherwise.

  17. I smoked k2 only one time sine know what really what the effect of it. Today, I suppose that I have DPD disorder. I live in France, so psychiatre don’t really know what is this stuff…Do you thing that TMS can cure me ? Or I can consider that I sill suffer all my Life? Thanks to your help

  18. my friend smoked this before and she did it maybe three times but the first time she did nothing happened then the second and she blacked out she didnt even know who i was. she stupidly did it again and she tripped out everything she said was numb and now she feels like when she looks at things she said she can feel the high coming back. shes young and she has school coming up what do i do to help ?

  19. I believe my daughter may of been effected by k2. She is now in a mental hospital with paranoia, delusions, and hallucinations. They are looking into sending her to a long term facility because she just isn’t snapping out of it. Have you heard of anyone else having these symptoms prolonged like this?

    1. Hi Denise. Because synthetic marijuana is never the same in chemical composition, and it’s a relatively new drug, not many clinical studies or reports on the long-term psychological symptoms have been done. However, many past users have experienced mental issues upon quitting synthetic marijuana, and the symptoms you describe can resemble those of others.

  20. Hi. I’ve been smoking k2(specifically the different flavors of smacked) for a little over a year now and have now started to see some symptoms. As I write this my hands and feet are sweating profusely while I lay in bed with the fan on practically high. I would consider myself a healthy person, but i dont find these effects normal. Previous to this k2 habit, I was a 5year weed smoker. Unfortunately I can say I am addicted (not to k2 but to smoking in general) as the longest I’ve went without it was 2 days so its hard for me to judge what’s normal k effects and what might be my own bodily complications. After smoking sometimes I feel a bit restless and anxious, then the feeling of having to pee rushes over me but only momentarily and then is followed by the sweaty hands feet and groin. This has only been happening consistantly for the past few months. I first experienced this while a couple months pregnant. Had a bad day and decided to smoke a blunt. Afterwards I couldnt sleep for like 2 days and eventually went to the hospital because I couldn’t stop throwing up( because I was pregnant) had no appetite and was severely dehydrated but kept sweating. I have a history of low blood pressure and an iron deficiency so that could’ve just been the perfect storm so to speak. Has anyone else had complications such as these?
    If symptoms persist I’ll definitely be switching back to weed or nothing at all.

  21. I am very addicted to spice. I have tried to stop several times. Now my whole life depends on quitting. I feel awful. I have been researching side affects of quitting and I have a lot of them. I have not seen diarrhea on any of these sites but I have had it really bad. Is this part of the withdrawals?

  22. Hi Patrick. The truth is, scientists still don’t know all the ways Spice may affect human health or how toxic it may be, but one public health concern is that there may be harmful heavy metal residues in Spice mixtures. Another problem is that mixtures of synthetic marijuana vary greatly.

    Without further analyses, it is difficult to determine whether you have someting to be concerned about. I’d suggest seing a doctor and getting some tests done in order to determine what’s wrong.

  23. I had smoked K2 about 2 months ago and had stopped.Currently i am having severe heart palpitations/anxiety attacks and have had a loss of appetite.Are effects of spice reversible?Who should i reach out to in my condition?

I am ready to call
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