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, you should check out this guide.