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How Long Does Marijuana Stay In Your System?

By on March 28, 2013

Summary (click to view)

  • Urine and blood screens are the most common tests for marijuana
  • Blood tests measure THC levels while urine tests measure THC-COOH levels
  • THC is broken down by the liver into THC-COOH and other metabolites
  • Frequent users may test positive for THC and THC-COOH up to weeks after intake
  • Infrequent users will be clear of THC and THC-COOH after 1-2 days 
  • The amount of time it takes to clear a drug test varies greatly from user to user 
  • TruthOnPot.com – All marijuana users are faced with a common problem when they are asked to undergo a drug test. The issue is that marijuana can be detected in the body for days or even weeks after last being used.

    How long it stays in your system depends on how frequently you use marijuana as well as your body’s rate of metabolism.

    Urine vs Blood Tests

    Urine tests measure levels of THC-COOH, not THC. Image source

    Urine tests are the most common way of testing for marijuana, but blood tests have been used as well, especially when driving under the influence is suspected. Blood tests measure levels of active THC and therefore can only detect recent marijuana use.

    On the other hand, urine tests measure levels of THC metabolites – the compounds that result from the breakdown of THC – such as THC-COOH. THC metabolites are known to remain in the body for much longer and therefore pose more risk to users being tested.

    A study published in 2007 by National Institute on Drug Abuse (NIDA) researchers summarizes the findings of previous research on the absorption and elimination of THC associated with marijuana use.

    THC From Smoking Marijuana

    Smoking is the most common way of using marijuana and also happens to be the fastest method of absorbing THC.

    THC has been found to be immediately detectable after the first inhale of marijuana smoke, with blood levels of THC reaching a peak at around 9.0 min into smoking – just under a minute before the patients took their last puff (9.8 min).

    While patients seem to control their individual doses by varying how deeply they inhale, the average amount of THC in the blood dropped to 60% of the peak at 15 min after the last inhale and to 20% at 30 min. By the 2 hour mark, THC levels were below 5 ng/ml.

    It took between 3 to 12 hours for THC to drop below detection limits (0.5 ng/ml) for the low-dose group and from 6 to 27 hours for the high-dose group of the study. However, the subjects of the study were not regular marijuana smokers, which explains why THC levels fell so quickly.

    THC From Oral Ingestion of Marijuana

    A less common form of consuming marijuana is by oral ingestion. Oral ingestion of THC leads to a very different pattern of THC levels. A study involving patients given 20mg THC cookies found the peak in blood levels of THC to occur between 1 to 5 hours following consumption. Another study conducted by Kim and Yoon (1996) using 10 mg THC capsules of Marinol identified a peak between 1 to 2 hours following ingestion.

    In studies involving hemp oils and dronabinol, THC blood levels were found to fall below detection limits (0.5 ng/ml) by 25 hours following intake. On the other hand, THC-COOH was still measurable for more than 50 hours after the last dose.

    THC Absorption

    THC blood concentrations decrease rapidly after you finish smoking due to its fast distribution into tissues and metabolism in the liver. THC is a fat-soluble molecule and is initially absorbed by organs with high blood circulation, such as the lung, heart, brain and liver.

    THC and its metabolites are usually retained by organs of the body for much longer than it remains in the blood. Studies show that THC is mostly stored in fat tissues and – with regular use – can stay there for up to 4 weeks.

    THC Metabolism and Elimination

    THC is primarily metabolized by the liver, but other tissues such as the brain, intestine and lungs may contribute as well. Studies show that within 5 days – 80 to 90% of THC is eliminated from the body – mostly in the form of its metabolites. More than 65% is excreted in feces and 20% in urine.

    On the other hand, a study found that THC could remain above the limit of detection (0.3 ng/ml) in the blood of regular users for up to a month following cessation, although it varies by individual.

    THC in Urine

    THC is not found in its active form in urine samples, but rather as the metabolite THC-COOH. The results of urine tests have also been shown to vary greatly from user to user, even in controlled laboratory settings.

    For new or infrequent users, the window of time for detection (50ng/ml limit) is believed to last 1 to 2 days.

    On the other hand, studies have shown that regular users can test positive (20 ng/ml limit) for THC metabolites for up to 46 consecutive days following marijuana usage. In an extreme case, a heavy cannabis user of more than 10 years was able to test positive (20 ng/ml limit) for up to 67 days after last being exposed to marijuana.

    How Long Will I Test Positive For?

    Based on these findings, it is impossible to say for sure how long marijuana will remain in your system for. There are a number of factors that contribute to this uncertainty, such as the level of THC dose, method of intake, duration and frequency of use and your body’s metabolism rate. On top of all that, various drug tests have different levels of accuracy and cut-off limits.

    As studies have shown, the chances of testing positive for marijuana – even after a break in use – are much higher if you happen to be a regular user as opposed to someone who has just smoked once or twice in the past few weeks.

    • “Truth”onpot

      “Blood tests measure levels of active THC and therefore can only detect recent marijuana use”

      This is absolutely untrue. In DUID driving cases, crime labs can and do use gas chromotography to test for THC-COOH at extremely low threshold levels and gain convictions in zero tolerance states. So much for “truth” on pot. Get your facts straight.

      • Freedom Stillwagner

        you are absolutely right….Az is one of those states and the judges are even not letting the jury hear that defendants have medical marijuana cards issued by the state at a hefty fee mind you then are convicting sick patients of DUI up to 30 days after medical consumption…. source: The Az Republic newspaper Aug. 9th 2013 titled “Legal Fight Brews On
        Impairment In Medical-Pot DUI’s”

    • Eric

      I have not smoked in nearly a year. 6 weeks ago, I smoked approximately 4 grams and have not had any since. Today I tested positive on a strip test, and it was tested twice. I am somewhat overweight, but I exercise some each day. I need to know if the GC/MS test is also going to show positive.

      • fire115

        No it will not.

    • jason

      okay I haven’t smoked weed since june 20 2013, then on the january 23rd 2014 I smoked from a blunt about 5-6 hits…. how long will it take to remove the weed from my system.. im 6’2 175, I have a pretty fast metabolism exercise 3 times a week… I need to know because im about to have a job interview and be drug tested this upcoming month

    • jman

      Been smoking for 9 years 4 to 5 times a day. I just resently quit 4 weeks ago how long do u think it will take foe me to pass a piss test?

      • 420victim

        As a chronic daily smoker i just failed a pee test at 104 days without smoking anything in that time period,with some of the new testing methods weed is one of the hardest things to get out of your system.I did everything i read and was told to get it out of my system,i do not have much body fat and drank water to flush my self out but no luck at all.

        • bman

          is it possible that even though you went 104 days without smoking you may have been exposed to marijuana smoke? or that your living areas still have 3rd hand smoke? Im not sure if this helps

          • Jacquie

            There’s no such thing as second or third hand marijiana smoking. Once someone exhales marijuana smoke, it no longer has the thc in it. Therefore, you can’t get second hand from it. Im 14 and even I know this lol

            • Melissa Brennan

              Yes you will test positive through a hair sample,

    • Darian

      I do not smoke often at all, once every few months tops, but I did smoke about 2 weeks ago. I’m currently looking for a job and scared I’ll fail a drug test. I really need some advice of I should be clear or not. Should I air on the side of caution and take an at home test?

      • Heather Keller

        You’ll definetly be fine

      • Heather Keller

        It will stay in your system for up to 10 days if you’re not a heavy smoker

    • campy80

      What about saliva test?

      • Abram115

        Saliva tests are a joke. The saliva test only tests positive within 10-14 hours of use

    • BOB

      I recently had a edible chocolate bar… I took 1/16 of the bar and felt a light buzz that night. My drug test is going to be around 8 days away from the night when I took the edible. I’m 123 pounds and 5 6′. Do you think I’ll pass?? Please answer.

      • bob

        You may or may not be, it really just depends. THC stays in your fat, so the less fat you have the better. Try to do some running, and drink lots of water.

    • Doug

      Hey guys, for anyone who can answer. I have not smoked for 8 weeks now. Prior to that, I was a fairly frequent user. I was smoking a decent amount, i suppose for a month, roughly from thanksgiving to Christmas. Prior to that, I took 7 weeks off. So in the span of 19 weeks, i smoked for about 4 of them. And I have a drug test next week. Would you think I’m clean? To give you an idea, I’m roughly 6’1 and 225 lbs.

      And what are your thoughts on at home drug tests? Are they helpful?

      • damon

        fail!

    • serbian

      i smoked one small joint 10 days ago, and week before that one joint more. i’ve been drinking water for two days and today i am going to piss for a test. what do you think? positive or not? pls.answer

    • jed_hoyer

      if you smoke every day,do you really think you’ll be doing anything that requires a drug test?

    • Ferch

      I weigh about 220 punds, smoked 17 days ago for 3 days straight about 2 to 3 hits, I had a drug test today, any idea if I’ll pass?

      • jerry

        So did you pass

    • CAYJ

      I havent smoked in 6 months but used to be a heavy smoker.. I’m due for a drug test from probation Apr 7th. If I decide to smoke (ex: a half of joint) whats the chances of my drug test coming back positive in April?

    • dj

      Ok so I smoked about three weeks ago then like a month earlyer before that and I am worried that I am gonna fail a random

    • curious

      heavy smoker for years quit completely and passed a take home test after 18 days is this possible or should i retest

    • marcus

      I only smoked 4 puffs of a small joint but IRS the only time I smoked. I have a high metabolism and weigh 154. Its already been 8 days will it pass a drug screen if I have it soon

    • 72L65as

      I smoke for six months straight been clean for 7 days I am 6′ 7″ 340 how much longer would you think it would take for me to get clean or am I clean?!

      • jazz

        I smoked for over 8 years everyday and it took me 65 days to be clean

    • JC

      I am a fairly frequent smoker, probably 5 or 6 bowls a day for a few years. I’m very skinny (5’10″ 135 to 140 lbs) and have a very high metabolism. I eat like a horse and haven’t gained a pound in 15 or so years. I have a test coming up but will have been clean 28 days by the time I take it. I’ve had 4 or 5 good sweats recently and been drinking at least a liter of water daily as well as a gallon of cranberry juice in the past 5 days. Whatcha think, am I good?

      • vanillarapper

        bro youll be fine I have taken 30 drug tests and I weigh the same and I have a fast metabolism… weed will only stay more than two weeks tops… if you have a lot of fatty cells and don’t work out then you’re in trouble but youll be fine!

    • vanillarapper

      if you guys work out and eat healthy then you guys will be fine! I have taken so many drug tests due to probation cause im in texas and its sooo easy to pass a test! if you’re fat as fuck and don’t do shit but smoke weed then marijuana will be detected in your system for about a month… ps: I only smoke dank :)

    • kooky

      A few year ago I had a urine drugs test, I was so nervous like an idiot I lit up a dooby a few hours before. I panicked again and on route to the drug testing I drank two litres of water. Did the test and passed. I have another today but this is blood. I usually smoke like a joint-3 a day but Iv stopped for about a month. I’m female 5’4″ and weigh like 50kg. So I’ll let you know if I pass

    • Sasi

      I smoke last saturday and I have a drug test tuesday its been around 9 days and I don’t smoke at all just tried it and I have a drug test tomorrow which is Tuesday will I pass the drug test/?

    • Jacquie

      I smoke about a joint a day. Im 5’4 115 lbs. I’m a wrestler so I sweat and drink lots f water everyday, how long do y’all think it would take to get thc out of my urine?

      • Jacquie

        I forgot to mention I’ve been smoking for about a year now. I did stop for two months from December- February of 2014.