How Long Does THC Stay in Your Hair Follicles?

(Last Updated On: August 8, 2019)

Recent years have seen a massive shift in how Americans, the medical establishment, and state governments view the use of marijuana.

In spite of the federal government’s continued insistence upon keeping it illegal, nine states now allow legal recreational use. Twenty-nine additional states allow for medical marijuana use. And a handful more, while not outright legalizing it, have decriminalized marijuana.

How does all this progress translate into the workplace? If you’re lucky enough to be in a state with legal recreational use, does that mean no more drug testing?

Well, no. Not even close. All nine legal states have language in their laws that explicitly allow employers to drug test for marijuana, even if the employee does not show signs of impairment.

While cannabis advocates feel that smoking a joint is no different from having a glass of wine, most companies haven’t come around to that way of thinking yet.

A significant number of employers still require at least a pre-hire drug screening, and many also perform random testing on their current employees. And if you are in a job that has federal screening requirements, such as truck driving, there is no leeway here.

Types of Screenings

laboratory technician holding and labeling sample tubes of urine

Let’s take a look at five main types of drug screenings:

  1. Urine test: This is pretty straightforward. You pee in a cup, and someone checks the urine for evidence of drug use. This test is by far the most common form of drug testing used for employment and legal system purposes.
  2. Blood test: A blood test is the most accurate form of screening, but it is also the most invasive and expensive of all the options. For this reason, it is rarely used for anything other than for medical or legal purposes.
  3. Saliva test: Saliva tests are quickly becoming a popular choice for screenings because they are minimally invasive. A quick swab inside the mouth is all the tester needs to collect. However, it is also one of the least accurate screenings since it only reliably detects very recent use. Cannabis use has to have been within the last 4-10 hours for THC to show up in a saliva test.
  4. Perspiration test: This is one of the newer drug screenings on the market. The person submitting to the test wears a patch on the skin for two weeks. This patch collects the person’s sweat which then is tested for the presence of illegal substances. This form of screening is most often used in legal situations, such as child custody cases.
  5. Hair follicle test: Hair follicle testing is becoming more popular in some cases because it has proven to be better at detecting long-term, habitual drug use. It is more expensive than some methods, but it is a useful type of screening.

THC and Hair Follicles

woman looking worried at her pink magenta color hair.

There is quite a bit of information out there regarding urinalysis screenings, but hair follicle testing is much less-known, so there are fewer resources available for those concerned about a positive test result.

So how long does THC stay in your hair? Here’s what you need to know about this kind of testing and how long THC will stay in your hair follicles:

  • Hair follicle screening looks much farther into your past than other methods. This type of testing usually results in a positive test for those who have used cannabis regularly in the past 90 days. Some tests even claim to go back a full year. A urine test, on the other hand, typically only registers use within the past 30 days.
  • This test was developed to look for habitual users. An individual who uses marijuana on rare occasions is less likely to have a positive result with this screening compared to someone who indulges on a regular basis. For this reason, hair follicle screenings for THC or other substances are not suitable in situations such as car accidents when authorities are trying to find out what happened leading up to the event. These screenings are much more common in employment settings.
  • Hair follicle screening detects THC metabolites that attach to the root of the hair. Washing, dyeing, and styling will not affect the outcome of the test. It takes about 5-7 days after ingestion for the THC to reach the scalp.

How Does the Test Work?

A woman has pulled out a handful of hair and is sad.

If you are required to submit to a hair follicle test, you will likely need to do so within a few days of the request. The examiner will verify your identity before she collects the sample and then clip about 100 hairs from your head to submit.

If you are bald or have very short hair, she may need to get a sample of body hair instead.

The hair goes to a lab for screening, and if a positive result comes up, it will go through a second test to verify the results. Negative results are available within 24 hours; positive results require 72 hours because of the second screening.

How Can I Get a Negative Result?

Adult man with shaving foam on his face is going to shave his head

Hair follicle tests are sensitive, picking up THC amounts as low as one picogram per milligram, for those of you keeping track. Basically, it’s hard to sneak ANYTHING past this screening.

Here are some options to consider, keeping in mind that nothing is guaranteed:

  • Can I shave? Sure. Will it ensure a negative result on your screening? Probably not. Having no hair to submit will just mean that you have to go back when you do have hair. It’s also likely to raise the eyebrow of an interviewer who just saw you with a full head of hair. And a fresh haircut won’t help either since the examiner submits the 1.5 inches of hair closest to the scalp where THC concentrations are the highest, pun fully intended.
  • Can I shampoo it away? Nope. The THC metabolites attach themselves to the hair follicle and are in the hair to stay. Shampoos, dyes, and styling products will not change that. Don’t waste your money.

Bottom Line


Bearded man, wearing a green sweatshirt and sunglasses, smoking

Hair follicle testing is nearly impossible to fool. It is designed to weed out (again with the puns!) those who habitually use marijuana or other substances.

If you are an occasional partaker, you will probably pass just fine. If you are a regular user, and you know you will be job hunting in the coming months, you would be wise to take a break until it is out of your system and the new job is secured.

Are you worried about potential drug testing? While there isn’t anything we can do to prevent a positive result on hair testing, you might be interested in Quick Fix Synthetic Urine, designed for success in passing nicotine tests or our detox shampoo. You can shop here.



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