Nearly 8 in 10 US employers require some type of drug screening before hiring, with some continuing to use drug tests over the course of employment. About 7% of these employers use hair follicle testing, one of the hardest types to beat. Hair testing is often used for jobs in airports, casinos, and other higher-security positions. It’s also used by an estimated 10-15% of Fortune 500 companies—hair testing’s prevalence is growing, as it reliably detects regular drug use over a long period of time.

Since the hair follicle test shows use over a period of at least three months (and potentially much longer), it’s notoriously difficult to beat and, as with any drug testing method, abstinence is the best way to pass. That said, if you’re facing an impending hair follicle test, don’t panic! There are ways to beat the test and cleanse your hair of THC in time, without waiting months for it to clear naturally. Here, we’ll discuss the science of hair testing, then break down what works and how to cleanse properly.

What is Hair Follicle Drug Testing?

While many companies stick to the tried and true urine or blood drug tests to check for recent drug use, the hair test is able to detect THC in your system for a much longer time. A human hair stores a long history from when it sprouts, to the moment you decide to get a haircut. This history is also stored in all of your hair including arm and, you guessed it, pubic. This is one of the reasons why you should really think before shaving your head as your last result. More on that later.

A clinician will cut a small sample of your hair with the goal of collecting ~50 strands of hair. That sounds like a lot, but more often than not your administrator will be able to complete this in three very small snips. The sample is typically taken from the back of your head with respect to your classy hairstyle in mind. Again, if you’re bald or have opted to shave your head before your drug test, samples may be taken from other parts of your body.

How Does THC End Up In My Hair?

Your body processes THC and other cannabinoids in complex ways, causing cannabinoids and their various metabolic byproducts to end up scattered throughout the body’s different systems. THC initially finds its way to your hair, or more accurately your hair follicle, through your bloodstream in the blood vessels that supply those follicles.

Here’s where it gets a little bit interesting: THC doesn’t actually stay in your bloodstream that long. It typically only stays there for as long as you’re high (a few hours in most cases, though it can remain detectable in small amounts for up to two or three days in the heaviest consumers). So how does such a short-lived phenomenon yield such a durable record of your THC consumption?

The body breaks down cannabinoids in the blood quickly, but not quite quickly enough—some of the THC molecules find their way into the soft tissue surrounding the root of your hair (keep in mind, all the action is taking place beneath your scalp so far). Some of those THC molecules attach themselves to the cortex, or outer layer, of the hair strand itself, emerging from the scalp as a cannabis-infused hair about 5-10 days later.

How Long does THC Last in my Hair?

When it comes to drug testing, employers typically like to use hair drug tests for their benefits of going further back than urine drug tests and mouth swab drug tests. While technically there is no definitive time frame for how long THC remains in your body, it has been shown through several studies that THC lasts anywhere from one week to three months for THC to completely become undetectable from hair follicles. 

This, of course, is reliant on how often you use THC products, how strong the weed or strain is, your metabolism/diet, your body fat percentage, how often you exercise, and how much you perspire. See our chart below for how the hair drug tests compared to other times of drug tests

First Time User 1-2 Times a Month 3-5 Times a Week Daily Use
Urine Up to 1 Week 2 Weeks – 4 Weeks Up to 2 Months Up to 3 Months
Hair Unlikely 1 Week – 3 Months

1 Week – 3 Months

1 Week – 3 Months

Blood 6 – 24 Hours Up to 1 Week Up to 1 Week Up to 1 Week

First 24 Hours

First 24 Hours

First 24 Hours

First 24 Hours

As you can see from the chart above, the only potential benefit of a hair follicle drug test being administered to you is if you are a one-time or first-time user of cannabis. It is unlikely that after a light first smoke sesh you will test positive for THC from a hair test.

This is because these tests were originally designed with their purpose being to catch heavy drug users. However, occasional and daily users are still prone to show up on these tests as they are very accurate. Do note that hair drug tests can determine drug use as far back as twelve months, but typically, will only reach back about the three.

The Science of Hair Follicle Testing

Consuming cannabis in any kind of real quantity (beyond a single puff at a party once in a blue moon) will be detected in a hair test. A hair test is estimated to be 6-10 times more accurate than body fluid testing for drugs, meaning it’s much more difficult to beat than a urine screen or cheek swab.

If you consume cannabis with any kind of regularity, your hair will reveal “bands” of THC indicating periods of usage, resulting in a positive reading. It takes just the tiniest amount of THC to trigger a positive result, too: one picogram per milligram. For those at home who don’t routinely measure on that side of the metric system, a picogram is 0.000000000001 grams.

The only way to beat a hair test is to, or outer part of the hair shaft, a process which is definitely going to rough up the condition of your hair. You should realistically expect some damage before all this is over, though this can be remedied with a few deep-conditioning treatments and a keratin treatment if necessary. Save the restorative processes until, though, as waiting will allow you to strip out as much of the THC as possible with the cleansing shampoo.

We know it’s possible to cleanse your hair of THC, but how can you do this most effectively and, perhaps more pressingly, quickly? You’ll need a high-quality for certain; while we’ll discuss some home remedies, these are not backed by science and should not be used exclusively (also, they’re crazy damaging to your hair!). If you’re going to try them out, use them in conjunction with a

How to Cleanse the Hair Shaft of THC

So, since THC is stored in the outer cortex of the hair shaft, it is possible to cleanse it of THC. This process involves opening up the cuticle, allowing it to release THC molecules, which can then be washed away. This is the basic action performed by, which work by chemically forcing open the cuticle, allowing the product to penetrate deep into the hair shaft and cleanse it of THC. are designed to penetrate the hair in a way that is minimally damaging, making them much gentler on your hair than DIY options like washing with detergent (yikes!).

The first thing you need to do is stop consuming THC immediately. Don’t add any more THC to your bloodstream to be carried to your hair follicles and into your hair shaft. Second, purchase a cleansing shampoo like and, if you like, a secondary product like (shown in image below), and begin a cleansing regimen immediately.

Zydot Ultra Clean Shampoo Product Review

What should your cleansing regimen look like? We recommend washing with the (shown in image below) 10-15 times before your test (this may mean multiple washes per day, but that dream job is worth it!), and then using the before the test for a final deep cleanse. You can also supplement your washing routine with the—not only will it provide an additional deep cleaning in support of the Toxin Rid, but its three-part system also helps recondition hair after the cleanse, returning some of its shine and improve manageability. This can be a lifesaver, especially if you have chemically – or color-treated hair.

Old Style Aloe Toxin Rid Shampoo Product Review

Boost the Results with Home Remedies

If you want to boost your cleansing routine with home remedies, start by saturating your hair with white vinegar and allowing it to soak for 15 to 20 minutes. Then, use a salicylic acid acne treatment to further cleanse the hair. Finally, lather your hair with one cup of liquid detergent. Then rinse your hair completely, without conditioning (it will be DRY!). You can also color your hair using a box dye or bleach that uses peroxide developer (most do, but avoid direct dyes that don’t use developer and therefore lack the chemical cleansing effect of other colors) to help clear out some of the THC. You can repeat these steps as needed until your hair is cleansed.

It’s critically important to avoid contact between your hair and things like hats, pillowcases, and hairbrushes that could still be contaminated with THC. Be sure to change your pillowcase and linens, as well as use a fresh towel when cleaning so you don’t take the risk of re-contamination. Wash all hats, and perhaps purchase a new hairbrush to use on your cleansed hair.

Think Before You Shave your Hair

It’s common advice: just shave your head!  This is misguided for several reasons: for starters, if they can’t get a sample from your head, they’ll just take it from somewhere else on your body, like your armpit or chest.

Furthermore, assuming you went all in and shaved your entire body, rendering yourself unable to provide a hair sample, you’d most likely be failed on the spot (testing authorities aren’t stupid, after all). Even if you weren’t failed automatically, you’d still be subjected to a different type of drug testing so you wouldn’t be off the hook anyway. Shaving is just not a good solution and can create a new set of problems. It’s much better to stick to cleansing.

A Quick Note About CBD & Drug Testing

If drug testing is a part of the conditions of your employment, you might be concerned about the potential of CBD to cause you to test positive for THC. This isn’t an unfounded concern — however, there isn’t exactly a cut-and-dry way to answer it.

Much of the data we have about CBD is anecdotal, and its potential impact on drug testing is no exception.  There are very few peer-reviewed studies on the subject, and the ones available paint a rather murky picture:  avoiding full-spectrum products containing traces of THC can reduce your risk of a false positive, but that may not eliminate the risk entirely.  A single study (as yet unconfirmed) suggests that even isolate-based products may not be completely risk-free under certain circumstances.

If you are concerned about passing a drug test, you’ll need to consider this potential risk when deciding whether CBD is right for you. To learn more about the science of CBD and drug testing, check out our article for a more thorough discussion of how to minimize your risk of a false positive.


While it’s an intense process, cleansing your hair of THC to pass a hair test is possible! You’ll need to get a for best results and use it frequently before the day of your test. The more washes you can get in beforehand, the better! TestClear offers rush delivery on all their products so you can start your cleansing regimen as soon as possible.

We are happy to provide our readers with a custom TestClear coupon code for all detox products on the site, simply enter code: ‘TestClear10‘ to get 10% off of your order!