Testing the hair for evidence of marijuana usage is more unusual than other tests for several reasons. Unlike more traditional ones such as urine, blood and saliva tests, they cannot prove if an individual has used the drug recently. They are also more expensive than most other tests, which is why employers rarely use this form of drug testing.
Like more conventional tests, a hair test screens for the presence of THC COOH. This is a metabolite of THC—the active ingredient in cannabis that is responsible for the high you get from smoking or ingesting it. It forms when the THC is you blood passes through your liver. It is then stored in the fatty tissues around your body. This includes organs such as your heart, lungs, kidneys and the liver itself. It can also be stored in your body fat.
Over time, small amounts of the metabolite are released back into your system. Eventually they make their way out of your body through your faeces and urine. This process can take a long time, and the more you smoke, the more metabolites you will accumulate inside your body.
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How Do Hair Tests Work?
When it comes to your hair, the metabolites bind to the hair structure. The only well-known way to remove them from your hair is to cut it (there are however detox methods effective at beating the hair test, but more on that later). If you only smoked once in the last 3 months, enough THC usually doesn’t bind to your hair to be detected. It’s when you smoked two or more times that you generally may need to start worrying. When the THC metabolites are present in your hair, hair testing is able to detect extremely small amounts.
There is some debate about the fact that body hair grows slower than other hair, and so will show a longer history; but this is not the case. All hair grows at about the same rate, but body hair stops growing at a shorter length. New hair replaces old hair when it stops growing and pushes the old hair out once it has stopped growing. This is its dormant phase, and during this time no new drug deposits can get into it. Hair follicles can remain dormant for 1 to four months, but only 10 – 15% of strands are dormant at any one time.
To test your hair, a sample of 1.5 inches is required. It is taken from the root of your hair and the rest is discarded. If the hair on your head is shorter than this, underarm, leg and chest hair can be used. Even beards can be tested, but not pubic hair.
How Long Does Weed Stay In Your Hair?
There are two answers to the question. If you’re asking because of an upcoming hair follicle drug test, the answer is pretty much always around 3 months, because that’s how long these tests go back in time. They use 1,5 inches of your hair, which is approximately the length your hair grown in 3 months.
If you’re asking simply because of curiosity however.. The THC and/or its metabolites stays in your hair pretty much indefinitely, which is considerably longer than its duration in the rest of your system. Thus the logical way to get a THC-clean hair if you’ve been smoking would be to cut your current hair off and abstain so that new hair can grow out that has no THC metabolites in it.
How Accurate Are Hair Tests?
Most tests measure the presence of THC metabolites in nanograms per millilitre (ng/ml). Urine, blood and saliva tests usually have a threshold of 50ng/ml to 20ng/ml. If your test has a concentration higher than this, your sample may be passed on for further testing. But hair tests can detect a concentration of as little as 1ng.ml. This means they are exceptionally accurate.
And because the THC is constantly being released from the fatty tissues in your body over time, it’s difficult to prevent it showing up in your hair. Very infrequent users may stand a better chance of testing negative. However, heavy users will not be able to avoid a positive result as their systems will have accumulated more of the metabolites.
But they’re not always 100% reliable. In fact, hair testing is better at detecting the use of other drugs like cocaine and heroin. And while they will indicate that someone has used marijuana in the past few months, they cannot tell you if the person is currently using.
Can You Beat A Hair Test?
It is very difficult to mask the effect of marijuana on your hair. Regular shampoo isn’t strong enough to remove it because the THC metabolite literally bonds with your hair shaft. No matter how much time you spend washing it, the THC is so deeply embedded that it cannot be washed away.
Tempted to try something stronger like lemon juice or vinegar? You’ll just be wasting your time. Highly acidic substances won’t have any effect on the THC—but your hair will be shinier. How about something stronger, like bleach? This can be effective if done right, but you’ll end up doing a lot of harm in the process and likely be forced to cut the hair off soon after the test.
You would need a medical grade detoxification shampoo to shift the THC. These contain an acidic base that destroys toxins but doesn’t damage your hair. They are most often used to remove toxins from prescription medications and medication used during surgery. But these types of shampoo aren’t readily available to the general public. There is however Aloe Rid, which has the desired effect and is used by many specifically to cheat hair tests, and is the one I use as the core product when I have a hair test to pass along with some other synergistic stuff such as Ultra Clean.
However, if you’re a smoker, you might have a better chance of escaping detection. Tobacco and hookah smoke contains toxins with a chemical make-up that is very similar to THC. This almost dilutes the follicle and makes the THC metabolite harder to identify. Also, exposure to high levels of humidity can break down the metabolite in your hair faster.
With other tests, you can try and speed up your metabolism to help your body flush the drug from your system faster. But this doesn’t work when it comes to your hair.
A first time user is only safe for about five days as this is how long it takes for the metabolites to show up in your hair. Even an infrequent user will fail a hair test because they are able to detect marijuana usage going back for three months. And heavy users have no way of masking their usage.
Yes, it can be harder to detect than other drugs, but the problem with marijuana is that it tends to accumulate in your system. Unlike other organs that flush the system over time, it remains in the hair for much longer. Even cutting your hair doesn’t help because it affects all the hair on your body. When it comes to drug testing, hair testing is the most difficult to cheat.
That being said, it’s definitely not impossible and there are good ways to get around it, although few, and somewhat costly. For what’s considered the most consistent way of beating the hair test, check out this guide.
21 thoughts on “How Long Does Weed Stay In Your Hair? (And Hair Test Workaround)”
See I haven’t smoked for over 5 months about. I didn’t smoke a lot. Maybe. A few times A month. Not even. Where I’m applying to I feel like they will do this test. I’ve had haircuts between the time I quit. Do you think I will pass? I never had long hair just I wanna be sure.
I think it’s been 4-5 months or something like that
Hey Chris, that’s way longer than the standard 3 month time-frame these tests screen for, so you should be in the clear here
I’m a heavy smoker and was wondering if the The Macujo Method works for short course hair or does it work for under arm hair.
Hi there, it should work on all types of hair although when it comes to under arm hair shaving might be easier without being all too suspicious. But if there’s hair available on your head, it’s unlikely your under arm hair will be tested in the first place
What are the chances of someone passing a hair test having smoked 2 months prior to. Only took 2 puffs and not a regular smoker but also took two puffs prior to thhose 2 months.
Hard to put a number on it, but hair tests can definitely miss it sometimes if you only smoke once in the last 3 months
I have a hair test coming. I’ll have been about 100 days clean. I smoked daily prior to my sobriety though. I’ve read in other posts that i’m in trouble. I’m 40, in good shape, have thinning hair. What are your thoughts?
Hi Mike, in general 90 days is the cut-off of how far back they go, although it depends a bit on how fast your hair grows compared to average as well. Since it’s so close to the limit and you were a daily smoker before, I’d still be a bit worried here and take some precautions (see guide on passing hair tests on this site). But the longer you wait after these 100 days, the less you need to worry, because I’d say you’re either already clean or on the verge of becoming so as far as hair goes
I smoked a joint mid June but before that it had been 4 months since I smoked. Will it take 90 days to be clear?
Sometimes hair tests can fail to detect it if it’s just a single occasion, but still a bit risky, so yes, 3 months to be sure. Or do some hair detox
I have a hair test in a week and i took 2 puffs about 2 1/2 months ago. I’m not a frequent user & that was the first time smoking in 6 months for me. Do you think I’ll be clear?
Hard to say. Sometimes hair test can fail to pick up on a smaller single-time use during the last 3 months, but for a very important test I’d certainly not want to rely on just luck. You may wanna check out the article on passing hair tests on this site for further info to stay on the safe site, either way I hope it goes well for you!
last smoked mid april, hair test was 8/9/2018, hair was taken form my legs, I shaved my legs bald twice once in june and once early july, awaiting my results …whats my chances you think
If I’m understanding this correctly, you’ve not smoked for nearly 4 months but also shaved the tested hair spots clean twice since you stopped. I’d say you passed this one without a doubt.
Can you pass after 48hours? With like proper detox?
Well, that may often even not be enough time for that hair to have grown out of the scalp, so yeah certainly
Hi. I stopped smoking 100 days ago. I test clean on urine sticks at under 25ng. I have no shaved all my hair. Will this new hair be clean to pass a hair test when it grows to 1.5 inches ??? Thanks.
Yeah it should be, whether you cut it or not, since they test the last outgrown part of the hair either way to get the most recent 3 months
Hi I’m not a heavy user at all but the last time I smoked marijuana was on 07/27/2018 and the last usage prior was on 12/03/2017. I have a hair drug test in next few days so should I be ok?
Yeah that’s plenty of time so should be just fine, again, 3 months is the general rule, anything over 4 and you should really be in the clear onless it’s a specific test goigng longer back than what is standard (which is very rare)