More or less, eight out of ten employers in the United States require their employees to undergo some kind of drug testing before they are hired. Some of them continue to use drug screening throughout employment. About 10% of the employers use hair drug screening, one of the most difficult to cheat and impossible to fake, method available today.

Hair follicle testing is usually used to test employees working in casinos, airports, government agencies and other high-security positions. It is also used by more or less ten to fifteen percent of Fortune 500 companies, the testing’s popularity is growing exponentially because of its reliability compared to a traditional testing method like urine and blood screening.

Since the follicle test will show the drug use over three to four months or 90 to 120 days, the method is very difficult to beat the test and impossible to fake compared to other methods like urine screening. You can use artificial or synthetic urine to fake the test or drink a lot of water to dilute the urine sample; abstinence is the best way to pass this test.

Marijuana by Using My Hair

With that being said, if you are facing a scheduled follicle drug screening, do not panic. There are a lot of ways to beat the method and cleanse your follicles of THC in time for your scheduled drug screening, without waiting weeks or months for your body to naturally get rid of it. In this article, we will discuss the science behind hair testing and break down what methods of cleansing will work.

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What is follicle drug testing?

While there are still companies that stick to conventional methods like urine and blood screening to check for any drug particles in the system and know the recent drug use history, follicle drug screening can detect THC or tetrahydrocannabinol in the system for a more extended period.

Our hair can store a long history of drug use, from the consumption date to the moment that you decide to cut your hair. The history can also be stored in all parts of your body with follicles including the neck, back, chest, arms, armpits, legs, or in your private parts.

It is one of the reasons why users need to think first before shaving your head to avoid drug detection. A laboratory technician will cut a small sample (more or less 100 strands). It sounds a lot, but traditionally, they will only need three to five strands.

The remaining strands will be used for confirmation or if the test requires a retake because the result is inconclusive. The sample is usually taken at the top or at the back of your head (to make sure you do not look like a bald eagle after). Again, if the subject is bald, they can collect samples from other parts of your body.

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How does tetrahydrocannabinol end up in your hair follicles?

The body process tetrahydrocannabinol and other cannabinoids in a very complicated way, and it causes cannabinoids and their metabolic byproduct to end up trapped in different parts of your body including in your follicles. Tetrahydrocannabinol initially finds its way to your hair via the bloodstream in your blood vessels that supply nutrients to your follicles.

Here’s the exciting part: tetrahydrocannabinol or THC does not stay in the bloodstream very long. It only stays there for as long as you are under the effect of the drug (usually hours after ingesting the substance, small amounts can be traced for up to two to three days for heavy users). So, how do follicles record the consumption for at least 90 days or three months?

Our body breaks down the cannabinoids in our blood quickly, but not quick enough – there are tetrahydrocannabinol molecules that find their way into the tissues surrounding your hair roots. Some of the particles attach themselves or trapped to the outer layer or cortex of your hair. Thus, emerging from your head, a cannabis-infused hair five to ten days later.

How long will it last in your follicles?

When it comes to testing, companies usually like to use hair as a sample because it goes further back in drug use history than urine or blood sample. While there is no definitive amount of time for how long tetrahydrocannabinol will stay in your body, studies show that THC will last from one week to three months or seven to 90 days for tetrahydrocannabinol to completely become undetectable from your follicles.

This method is, of course, relies on how often you smoke cannabis-infused products, the strength of the strain, your diet, how fast your body metabolizes the chemicals, the percentage of your body fat, if you exercise regularly or how much your body sweat.

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Marijuana by Using My Hair

The only advantage of being subjected to this method is if you are a one-time cannabis smoker or you are not a regular user. There is a small chance that after smoking one puff, you will test positive for tetrahydrocannabinol from a follicle test.

The reason for this is because the trial was initially designed to catch heavy users. But an occasional or daily users can still test positive since this method is very accurate. You need to know that follicle drug screening can determine drug usage as far as one year or twelve months, but usually will only reach back for about 90 days or three months.


While this method is a very intense process, cleansing your follicles of THC to pass a hair screening is possible, all you need to do is find a right hair detoxification product or shampoo and make sure to use it religiously before the scheduled day of the screening. The more you use the product beforehand, the higher chance you will pass the test with flying colors. Although this method is not 100% reliable, even 1% of chance that you will pass is a big help especially if your job is on the line.