One hit of weed hair test
Most of us have had to pass a drug test, so an employer — or worse, a court — can see if we smoked weed. But one of the most dreaded drug screenings is the hair follicle test, which is said to be highly accurate and offer a long window of detection. In some instances, hair tests can detect THC in samples up to a year after someone last blazed.
But how long does weed actually stay in the hair, on average? And if you know that a follicle test is coming, is there a way to beat it?
How Weed Gets Into Your Hair
Hair follicle tests use small hair samples, typically 1 centimeter in length, to find traces of THC or THCA, the intoxicating components of the marijuana plant. THC can end up in the hair one of two ways: through oily excretions on the smoker’s skin or by second-hand contact after the hair gets exposed to weed smoke.
The first scenario, where a person’s own skin oils transfer THC metabolites from the blood to the hair, can lead to reliable detection of past cannabis use. Why? Because THC is fat-soluble — meaning it absorbs through fat, not water — and an individual’s metabolism plays a big role in how long THC remains in the body (and how much ends up in the hair). Those with more body fat will retain THC in (and on) their bodies longer than those with less body fat.
How frequently someone smokes weed can also increase the window in which weed is detected via hair. A study from 2017 showed that folks who toked daily came up positive for THC on hair tests 77 percent of the time. Less than half of those who smoked weed on a weekly basis tested positive. Every subject who hadn’t smoked within three months of the test, or who reported never smoking weed at all, came up negative.
The study’s results suggest that those who consume cannabis infrequently could luck out on a hair test. But chronic connoisseurs of the dank would need to abstain from smoking for weeks — if not months — to achieve negative results.
Beating a Hair Follicle Test
But first, let’s get the bad news out of the way: you probably can’t cheat a hair test.
Some companies market detox shampoos for washing THC out of your hair, but they’re all — as far as we’re concerned — questionable products. Hair tests work because hairs trap THC in their microscopic fibers as they grow. Shampoos can wash off THC on the surface of the hair, but they can’t remove THC that’s embedded inside of the strands.
Second, shaving off your hair prior to a follicle test won’t accomplish much, either. Samples for hair tests can come from any part of the body, including the little hairs inside of your nostrils or ear canals.
Besides, showing up to a testing facility without any eyebrows will raise the testers’ suspicions that you’re cheating, and that alone can disqualify you as someone who’s clean and sober. So unless you’re undergoing chemotherapy or you’re a champion swimmer, you’ve got no good excuse for being balder than a newborn when it’s time for a drug test.
That leaves sowing doubt as the only way someone could wiggle out of a hair test’s results. Thankfully, there’s some solid science questioning the validity of hair tests and whether they can actually prove if someone recently got lit.
Are Hair Tests Just as Bunk as the Products Sold to Cheat Them?
In 2015, German scientists concluded that hair testing was wholly unreliable for determining if someone smoked weed. They gave test subjects pure THC or THCA in oral form, then looked at the hair samples. They discovered that only incredibly tiny amounts of THC ended up in the hair, much less than the 50 picogram/milligram detection limit (the absolute smallest amount that scientists can say they measured) set by the Society of Hair Testing.
Their conclusion? Hair tests weren’t detecting THC that someone inhaled, but rather the tests were finding THC that landed on the hair through external contact, like second-hand smoke. In other words, someone who is simply in the presence of weed smoke could come up as a false positive on a hair test.
“Our studies show that… cannabinoids can be present in hair of non-consuming individuals because of transfer through cannabis consumers, via their hands, their sebum/sweat, or cannabis smoke,” the researchers wrote. “This is of concern for e.g. child-custody cases as cannabinoid findings in a child’s hair may be caused by close contact to cannabis consumers rather than by inhalation of side-stream smoke.”
The following year, another German study found that just breaking up nugs and rolling joints – not smoking them – could also produce false positives on hair tests. The researchers hypothesized that fingertips contaminated with cannabis resin transferred THC from the hands to the hair after casual contact.
Problems with hair testing have been known for some time, too. In 2004, yet another German study explored several cases of false-positives with weed and hair tests, including one instance where a cohabiting couple both came up positive for THC through hair testing, even though only one of the partners smoked weed; the other did not.
Although American chemists have acknowledged the German findings, one paper in a 2016 edition of Analytical Toxicology claimed that false-positive transfers were rare, and washing hair samples in an alcohol and water mixture prior to testing could distinguish true cannabis consumers from those who simply walked through a cloud of marijuana smoke.
In the American study, researchers only looked for a single THC metabolite in the hair, 11-nor-9-carboxy-delta-9-tetrahydrocannabinol or C-THC. C-THC is one of the first THC metabolites made in the human liver, so it’s not present in marijuana smoke. Using a mixture of alcohol and water, THC from second-hand smoke can be rinsed from the samples, leaving behind only the C-THC trapped in the hair fibers. However, as per the 2015 Germany study mentioned above, C-THC can still end up in someone’s hair if they touched something contaminated with a toker’s skin oils or sweat.
So it looks like American authorities won’t be ditching hair tests any time soon. Thankfully, due to the costs associated with hair tests, most employers don’t use them, opting instead for much cheaper urine tests, which can be beat. And, thanks to adult-use regulation, some states have even removed cannabis from the list of prohibited drugs companies test for.
Although you could try to defend your hair test results to a judge or an employer using the cited German studies above, we don’t recommend it. Instead, find a good lawyer to do this for you.
The most dreaded of all drug tests is the hair test, which can detect THC up to a year after your last toke. But is there a way to beat a follicle screening without abstaining from weed?
How Long Does Weed Stay In Your System?
This article was made possible by a sponsorship from my friends over at passyourtest.com. Check out their site to find out how to reduce the amount of time THC is in your system.
The amount of time weed stays in your system is a pretty complicated topic. There are a ton of variables you have to include and a small mountain of research studies to go through. Also, the time varies based on what’s being tested i.e. urine, blood, hair, or saliva. The chart below is the sum of several weeks spent researching this topic in depth. I hope you’ll continue reading below where I break down all the research.
Here’s a text version of the chart above for those who are unable to view images:
Single Use 2-7 days
Occasional Use (few times per month) 7-20 days
Regular Use (few times per week) 20-30 days
Heavy/Extreme Use (daily+) 30-100 days*
*60+ days is considered highly unusual even for heavy smokers, but numbers as high as 95 days have been observed in clinical tests.
Single Use 1-2 days
Occasional Use 1-3 days
Regular Use 2-7 days
Heavy/Extreme Use 7-18 days
90 days. While it is possible to see a longer history of use, all standard testing methods for hair look at the last 90 days.
Single Use Table of Contents
There is a ton of information in this article. I hope you’ll read the entire thing, but if you need to know something specific use the links below to skip down the page.
[ps2id target=”/] THCCOOH & What It Means For You
Most people think of a marijuana drug screening as something that looks for THC. This isn’t quite accurate. The vast majority of screenings are looking for a compound known as THCCOOH. Here’s why:
THC actually lasts for only a few days in your system. So, labs typically turn to another compound found in marijuana, THCCOOH. Unfortunately, this has a much longer detection time than THC.
Note: There are a few tests that look at compounds other than THCCOOH. For example, some blood tests have used both THC and 11-OH-THC.
[ps2id target=”/]Factors That Affect THC Detection Times
One of the most important things to remember is everyone does not have the same detection times – not even close. Thus, there is absolutely no way for anyone to positively predict your exact detection time frame. I will do my best to guide you as much as possible, however, you must under the following factors to really understand how detection times work.
- Frequency: How often do you smoke? This idea will be covered more thoroughly throughout this article.
- Dosage: How much do you smoke at a time? Also, how potent is the weed?
- Weight: The more body fat you have, the longer it takes to clear a drug test.
- Exercise: Exercising speeds up the rate of THC detox. Are you are naturally active?
- Metabolism: A fast metabolism with result in shorter detection times
- Liver Health: Much of the THC you smoke is processed through your liver. If you have a liver condition it would cause you to process it more slowly.
- Test Sensitivity / Cutoff Level: Truth is, with most tests you can have a little bit of THC in your system and still pass. Tests have a set amount of THC that will still result in a negative test. Cutoff levels differ depending on what type of test/screening being used.
- Testing Method: Not all tests are created equal so some are more sensitive than others. For example, this study demonstrates how GC/MS (gas chromatography-mass spectrometry), when compared to Immunoassay testing, detects THCCOOH faster and for longer periods of times.
[ps2id target=”/]How Long Does Weed Stay In Your Urine?
Urine tests are perhaps the most prevalent type of drug testing that you will encounter. One reason is urine tests are much cheaper to perform than the other types of drug screening methods such as hair, saliva, and blood. Unfortunately, urine tests also yield the longest detection times with the exception of hair. The cutoff level for urine is typically 20 or 50 ng/ml, however; this number can vary.
[ps2id target=”/]Additional Factors Affecting Urine Tests
In addition to all the factors just mentioned, there are several factors that apply specifically to urine screenings.
- Fluid Intake: This factor really only affects urine tests. Drinking more water will dilute the amount of THC in your system. Drinking too much water could cause you to fail the test.
- Urine pH: Urine that is more acidic has a shorter detection time.
Okay, let’s get on to some real numbers, shall we? Perhaps the number one factor is how much you smoke. Below each category of usage, you’ll see a range of detection times. You can use some of the factors about to help figure out where you might fall within the range.
[ps2id target=”/]If You Only Smoked Once / Took One Hit
This category is for people who only used a small amount. If your one-time smoking was an all out bluntfest or a heavy dab session then you will likely experience longer detection times. Typically, people who smoke once will test positive for marijuana for 2-7 days. Again, depending on how much you smoke, along with the factors mentioned earlier, you could have a longer detection time. These numbers also assume you were completely clean before your one-time smoking.
Okay, let’s talk about the studies these numbers come from.
A study done in 2001 gives us several useful figures for single use. First off, they state urine typically does not test positive right away. The study found it took an average of 4-6 hours after smoking for marijuana to be detected. This number is largely dependent on the type of equipment used. That same study found an average detection time of 42-58 hours. This is roughly 1.8-2.5 days. Remember, these numbers are the average so individuals could be higher or lower.
According to an article published in the International Journal of Clinical and Laboratory Medicine, after smoking one marijuana cigarette, THC is detectable in urine for 2-4 days.
Several websites cite A research paper by NDCI claiming single use is detectable for 5-8 days. These figures, however, are simply an endnote. The endnote references a site that sells products design to help you pass drug tests. The specific reference page does contain the same figures, but no actual source is to be found anywhere on the page. It’s basically the word of people who directly profit from people thinking they’re going to test positive. I’m not saying these numbers are wrong, but I’m just not seeing real proof.
Also, it seems the 5-8 days was taken out of context. If you read the NDCI paper you’ll find the author actually recommends this: “At the 20 ng/mL cutoff for cannabinoids, positive urine drug test results for the single event marijuana use would not be expected to be longer than 7 days.”
[ps2id target=”/]Occasional Use
An occasional user is someone who consumes cannabis several times per month. Occasional users will typically have a detection time between 7-20 days. Most people will be clean in less than 2 weeks, but as always, exceptional cases are possible.
Truth is, there is not a ton of published research on this group of people. Most of the research focuses on chronics users or one-time users.
If you’re spreading out your smoke sessions then it’s possible you’re getting clean before your next session. If however, you’re smoking about once a week then it’s possible for the THC to build up resulting in a longer detection time.
[ps2id target=”/]Regular Use
A regular user is someone who consumes cannabis several times per week. 30 days has been the long-standing “gold standard” for THC detection time in regular users.
This number has come under some scrutiny, however. Some researchers believe the detection time is much less. The NDCI study mentioned earlier, which aims to set detection boundaries for courts, claims it would be unlikely for a regular user to test positive after 21 days. The problem with this number (and the article in general) is it doesn’t discuss all the individual factors such as body fat and exercise.
So, while most people will be clean in 20-30 days, it is possible for regular users to test positive for longer.
[ps2id target=”/]Heavy Usage / Extreme Cases
A heavy user would be someone who smokes daily (or close to it). Heavy use over a prolonged period of time also increases your detection times. Using heavy concentrates may bring your number up as well. Typically a heavy cannabis user will test positive for 30-60 days, however, much longer times have shown up in published research. Extreme and unusual cases could test positive for 100+ days.
The National Drug Court Institute took a look at 8 different studies. Of these studies, 4 relied on subjects who were self-reported heavy or chronic users. The longest detection time from each study was: 40 days, 67 days, 25 days, and another study also found 25 days to be the maximum time to test positive. Keep in mind these studies were done in the mid to late 80s so they may not be directly comparable to modern cannabis. Also, note many of these studies relied on relatively small sample sizes of participants.
Ellis et. al. found that out of 86 patients, who described themselves as chronic users, the average detection time was 27 days, but could take as long as 77 days.
Now, a quick look at the extreme cases. There are at least 2 documented cases of people testing positive in excess of 90 days. In 1991, a study by Lafolie P. et. al. had a participant who tested positive for 93 days. A year later, another study found a participant who tested positive for 95 days. Both of these studies were conducted in the early 90s when weed was not as potent as it is now. It would not surprise me to find extraordinary cases of people testing positive for 100 days given the high potency of modern cannabis.
[ps2id target=”/]Detection Times For Marijuana In Your Blood
Your blood will test positive for THC for a much shorter detection period in blood as compared to urine. THC detection times for blood are typically a week or less, however, extreme cases have tested positive for over a month.
[ps2id target=”/]One-Time Use
Most one-time users will typically be clean for a blood test in 1-2 days. Some users have shown to test negative only 6 hours after use.
A 1992 study found that participant’s blood tested positive for THC-COOH for 6-27 hours after smoking a single “high-dose” marijuana cigarette. Keep in mind high-dose is referring to marijuana that is 3.55% THC. This number is up to 10 times less potent than modern weed. For this same study, a low dose joint was 1.75% THC. These subjects tested positive for 6-12 hours after smoking. So, you can really see how potency of your weed matters when it comes to detection times.
Another test, using the same potency weed as the previous study, found that test subjects tested below 1 mg/ml. This study only included 6 participants.
[ps2id target=”/]Occasional Use
If you’re only smoking a few times per month then you should have fairly low detection times. In fact, it’s possible you are getting completely clean between usage if you’re spacing them out. Expect to test positive for 1-3 days after occasional use.
[ps2id target=”/]Regular Use
NORML (National Organization for the Reform of Marijuana Laws) published a statement claiming regular users will typically test positive for 2-7 days.
[ps2id target=”/]Heavy Use / Extreme Cases
A heavy user may be detectable for cannabis in blood for 7-18 days. This number is much higher than the 7 days many sites are suggesting, however, these numbers are entirely rooted in peer reviewed scientific research. Also, keep in mind that the higher end (18 days) is reserved for extreme cases.
Here’s a study I find exceptionally interesting and important. There is 3 reason’s I’m so interested in this study:
- It was done in 2013. Many of the studies done on the subject are decades old so it’s always good to have newer research.
- The participants used their own weed instead of administered weed. This is important because administered weed is typically very low strength compared to what the general population is smoking. Many of the old studies consider 3.55% to be high-potency (lol).
- This study found some numbers that are much higher than many of the old studies.
Okay, so let’s dive right into it. This study looked at 22 people who self-reported smoking a median of 9 joints per day. Also, all participants reported regular use of cannabis for over a year prior to the study.
The study analyzed 3 different markers for the screening: THC, THC-COOH, and 11-OH-THC. Both THC and THC-COOH were found up to 30 days after subjects stopped smoking. Now, let me say, there were 2 subjects in the study who reported smoking for 15-17 years and 9-18 joints per day respectively. So, keep in mind these are extreme cases. Also, although THC was detectable for 30 days, the cutoff of ≥5 ng/ml for THC-COOH, was not reached after 18 days. The ≥2 ng/ml cutoff for THC was not met after 9 days. Lastly, 11-OH-THC showed 0 participants testing above the ≥2 ng/ml cutoff after 24 hours.
These cutoff numbers are important as they have been cited multiple times as proposed levels for impaired driving in states and countries where cannabis is legal. This means heavy users could test positive for intoxicated driving even if they hadn’t smoked for 16 days.
[ps2id target=”/]How Long Does THC Remain In Hair Follicles?
Hair testing reveals marijuana in your system longer than any other testing method. It’s also a very uncommon test to have done. While it is possible to see a longer history of use, all standard testing methods for hair look at the last 90 days. Also, if you think shaving your head will do the trick then think again. The test can also be done on body hair so you would have to shave your entire body smooth (don’t forget about those eyebrows).
[ps2id target=”/]How Long Is Weed Detected In Saliva / Mouth Swab?
Like blood, the detection times for saliva are much shorter when compared to urine screenings.
[ps2id target=”/]One-Time Use
The majority of one-time smoker’s saliva will test negative for marijuana in less than 24 hours.
This research took a look at 6 other studies who looked at saliva testing on marijuana users. It found detection times to range from less than 6 hours up to 14 hours.
Niedbala et al found subjects tested positive for 13-34 hours after one-time use. However, this test used a .5 μg/L cutoff level which is double the typical cutoff of 1 μg/L for a GC-MS test.
[ps2id target=”/]Occasional Use
Due to the small window of saliva detection time most occasional users (smokes a few times per month) shouldn’t take much longer than a one-time user to naturally detox (24 hours).
[ps2id target=”/]Regular Use
Using a few times per week may increase your detection time. Olaf Drummer did a meta analysis in which 4 different studies were analyzed. He found the longest detection time to be around 30 hours. So, regular users could possibly test positive for up the 3 days.
[ps2id target=”/]Heavy Use / Extreme Cases
Extreme cases could see saliva detectable for up to 7 days, however, this amount of time would be considered unusual. The actual time is going to vary based on your individual variables.
If you’re trying to reduce the amount of time THC stays in your system don’t forget to check out passyourtest.com.
Thanks for reading! Let me know what you think in the comment section below. Also, if you enjoyed this article then here are a few more I think you might like:
How long is weed in your system? This article covers urine, blood, hair, & saliva testing. Get times for one-time users, occasional, regular, & heavy users.