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Home / Drug Testing / How Far Back Does a Hair Follicle Test Go?

How Far Back Does a Hair Follicle Test Go?

March 19, 2025 by Amie Powell

Last updated : May 12, 2025

The hair follicle test is more expensive than the urine and saliva tests but companies that choose this method of employee drug testing find it more cost-effective in the long run. Why? It affords employers a ninety-day detection period. When comparing the difference between the hours, days, or weeks of detection that other test methods provide to the three months of detection afforded by the hair follicle test, it’s easy to understand why it should continue to grow in popularity.

Urine tests account for over 90% of annual employee drug tests. Only 7% of employee drug tests are completed using hair samples with mouth swabs, otherwise known as oral fluid, tests. The hair test still has a way to go to be a contender for the most used employee drug test but it’s gaining ground.

Three-month detection

Truth be told, there’s no limit to the length of hair that can be tested for drugs. That’s because once the metabolites leave the hair follicle they fuse with the hair shaft and remain forever.

The standard length of hair used for a drug test is only one and one-half inches. Lab technicians cut the hair sample provided to test length and toss the rest. Human hair grows about half an inch per month,so one and a half inches of hair equals a 90-day detection period.

The hair follicle drug test is widely used in court proceedings because it determines whether or not drugs have been used for an extended time. If the court system requests a longer identification period, laboratories accommodate the request by testing longer hair samples.

You aren’t washing it out

There are products on the market, mainly shampoos, claiming to remove any signs of drug use but they don’t work because, as we mentioned, the metabolites become a part of the hair shaft as they exit the hair follicle. Homemade concoctions utilizing acne medication and vinegar—among other things—that claim to “detoxify” the hair aren’t any better.

There’s another method called the “Jerry G.” It claims to fundamentally change your hair erasing drug metabolites if you carefully follow the 8-step process. It’s weed-specific, though, and doesn’t work if the person continues smoking while undergoing the “transformation.”

The proedure involves bleaching and then re-dying the hair using a hair dye that contains ammonia. Afterward, the user must wash the hair with “Toxin Rid” and allow the hair to air dry. Repeat the process ten days later and—presto, change-o!—your hair magically transforms. All you need to do is wash your hair once more with the name-brand shampoo on the day of the test and you’re “guaranteed” to pass.

We feel obligated to warn you that the article in which we discovered the method stressed more than once that you do not want to use a blow dryer after the bleaching and dying process. Your hair won’t be in any condition to handle the heat and could easily break off.

Eeek!

We can’t help but wonder if anyone ever showed up for their drug test in shock clutching their frazzled hair sample in their hands. If ever there was an appropriate place to insert an “smh,” it would be here. Agreed?

DOT notes the advantage

The Department of Transportation has planned to switch from the urine test to the hair follicle test for years now. However, there have been a few hold-ups along the way. One pertained to whether or not hair testing was affected by environmental factors or hair products.

After successfully putting these concerns to rest, the DOT officially entered the request for approval to discontinue the urinalysis drug test using the hair follicle test instead. It continues to circulate through the chain of command and while it isn’t expected to meet with resistance at any level, things seem to be moving ahead at a snail’s pace.

The trucking industry supports the DOT’s decision to use the hair follicle drug test. Were you aware that some employers in the industry are already doing so? They utilize both the DOT drug test and the hair follicle test. They willingly incur the added expense of a second drug test due to accessing the lengthy identification period.

Considering that many employers of the general workforce mimic the DOT drug testing policies for their employees, once approved, the hair follicle test well may eventually overtake the urine test as the most commonly used method for employee drug testing.

It started getting hairy

Scientists created the hair follicle and mouth swab tests in the late 1980s. Cheaters were discovering ways to falsify the urine test with additives, or diluting the test by drinking excess fluids.

It’s hard to alter the outcome of urine tests now. Continued advances in urine testing technology make it increasingly difficult for anyone to tamper with the test results. Still, since privacy is required to obtain the test sample, desperate drug users keep trying to get over on their employers.

Obtaining the sample

Privacy is no big deal when submitting a hair sample. The technician gathers a group of hairs, about the width of a #2 pencil, from the underside of the hair. Then, they snip the hair as close to the scalp as possible. The sample is prepared for transport and the employee signs off completing the test.

There’s no way to substitute the specimen because the technician collects it and hair can’t be “prepared” beforehand.

The wave of the future

Will the hair follicle test overtake the urine drug test as the most popular employee drug test on the market? That remains to be seen, however, it’s completely feasible after the DOT sets the bar. The advantage of a longer detection window is hard to overlook.

Drugs in the workplace are a thorn in the side of every business owner. Someone impaired by drug use is at higher risk of causing an accident. They put both themselves and everyone around them in danger. That’s the main reason that employers implement a drug-free program.

Employee drug use causes employers to lose billions of dollars a year due to increased absenteeism, tardiness, frequent doctor’s visits, and lowered productivity though employee testing markedly cuts down those expenses.

If you have an employee who tests positive for drug use, do your drug-free policies include passing on a list of resources? Someone who uses drugs is likely to disregard the pleas of friends and loved ones to seek help. They, often, mentally justify their actions in whatever way necessary so they can keep on keeping on. However, as their employer, you may carry enough authority in their mind to give them cause for reflection.

A kind word spoken sincerely letting them know you care about them and their family may be the catalyst that causes them to make a change that, ultimately, saves their life.

We hope so.

Filed Under: Drug Testing

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About Amie Powell

Amie has over a decade of experience in the drug testing industry and specializes in helping employers maintain compliance with the industry's ever-changing laws.

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