What Is a Hair Follicle Drug Test?

Published Mon, April 25, 22

While rarely used, hair follicle tests are significantly more accurate and comprehensive than other common types of drug testing. A hair follicle test can detect drug use as far back as three months (90 days), and acquiring this extended history of an individual’s drug use may be important to potential employers or law-enforcement.

It’s highly unlikely you’ll ever be subjected to a hair follicle test even if regular drug testing is something you’re used to. To be adequately prepared, though, use this guide to figure out what a hair follicle test is, what it can detect, and how to prepare if you expect your hair follicles to be tested for drug use in the near future.

What is a hair follicle test?

A hair follicle drug test is a type of analytic procedure that uses one or more of your hair follicles to detect the use of drugs within the last three months. Most drugs and other substances leave tiny traces in your hair follicles that can then be detected using sophisticated laboratory equipment.

Hair follicle tests do not hurt, and some consider them to be less invasive and more respectful of your privacy than urine drug tests. The downside, however, is that hair follicle tests are usually more expensive than urine drug tests. As a result, they are used far less frequently and only in cases when it’s absolutely essential to detect drug use of any kind over an extended period.

What shows up in a hair follicle test?

Hair follicle drug tests generally consist of a five-panel screen that detects THC, PCP, opiates, amphetamines, and cocaine. As a result, the scope of hair follicle drug testing is considerably more limited than the scope of urine drug testing, which usually detects the presence of 12 different illicit drugs.

Many of the drugs screened for using urinalysis, however, simply do not leave traces in your hair follicles. Also, the considerable cost of hair follicle drug testing makes it more prudent to focus on a smaller group of substances.

Can a hair follicle test detect one-time use?

In some cases, hair follicle drug testing may detect the presence of an illicit drug even if you’ve only used it one time. Generally, though, this type of testing is used to detect chronic, long-term drug use that deposits considerable trace amounts of an illicit substance in your hair follicles over time.

It’s worth pointing out that hair follicle drug testing will not detect the presence of a drug that you only used a single time a few days ago. That’s because it takes a while for new hair to grow in. So, while there’s a small chance that subsequent hair follicle tests will detect that single instance of drug use, hair follicle drug tests are accepted as being essentially useless for detecting recent use of illicit drugs.

Can a hair follicle test detect THC?

Yes, delta 9 THC is one of the five federally illicit substances commonly tested for as part of a five-panel hair follicle drug test. Despite the fact that THC use has been legalized in many US states, delta 9 THC remains illegal under federal law, and some companies still concern themselves with detecting its presence in the hair follicles of potential or current employees. Detecting THC use is also common when you’re on probation, but in most cases, authorities use urine drug testing due to its significantly reduced cost and ability to detect recent drug use.

Can a hair follicle test detect delta 8?

Yes, hair follicle tests can detect the presence of delta 8 because this cannabinoid is an analog of delta 9 THC. The effects of delta 8 may be noticeably different from the effects of delta 9, but from a chemical perspective, these two substances are nearly identical. As a result, all forms of drug tests will be incapable of confirming that you used delta 8, a hemp cannabinoid, instead of THC, a marijuana substance.

Can a hair follicle test detect CBD?

No, hair follicle tests do not detect the presence of CBD since this substance is not one of the five drugs hair follicle tests are calibrated to detect. In general, CBD is not a high priority for drug testing since this substance is non-intoxicating and non-addictive. Regardless of which type of drug test you take, it is highly unlikely that CBD will be one of its targets.

Some types of CBD products, however, contain trace amounts of THC. If you use large amounts of full-spectrum CBD over an extended period of time, for instance, a follicle test may be able to detect the presence of THC in your hair. Since concentrations of THC in CBD products must be under 0.3%, however, you would have to use an incredible amount of full-spectrum CBD to result in a false positive on a hair follicle drug test.

How accurate are hair follicle tests?

Like all forms of drug tests, hair follicle drug tests are not 100% accurate. The quality of the hair sample tested makes all the difference in the accuracy of this type of testing, and a variety of factors can make your hair more or less suitable for drug testing. While false positives can sometimes occur, hair follicle testing is much more likely to simply not detect the presence of drugs in a hair follicle due to damage or alteration to the follicle sample.

Can a hair follicle test be wrong?

Yes, hair follicle tests are not entirely accurate. A variety of factors can remove the trace concentrations of illicit drugs hair follicle tests are designed to detect, but it is much more rare for a sample of your hair to show the presence of drugs you did not ingest. Someone exhaling cannabis smoke near your head, for instance, will not confuse a device designed to detect the presence of drugs inside the molecular structure of your hair follicle.

What can cause a false positive hair follicle test?

In rare cases, ingesting foods like poppy seeds or taking prescription medications can confuse hair follicle tests designed to detect illicit drug use. Hair follicle tests involve a two-stage process, however, that is designed to eliminate the potential of false positives, which is a major difference between urinalysis and hair follicle drug testing. In fact, hair follicle testing is often used to confirm or disprove a potential false positive provided by a urine drug test.

How does sweating affect a hair follicle test?

Excessive sweating cannot cause a hair follicle test to detect the presence of a drug you did not use. Scalp perspiration can, however, make it more difficult for a hair follicle drug test to determine when you used an illicit substance.

When you sweat, the trace amounts of drugs left over in your hair can make their way down the follicle, giving the appearance that you used a substance longer ago than you actually did. As a result, exercise or other activities that cause perspiration can help if you want to make it seem like you used a drug a long time ago rather than recently.

How far back do hair follicle tests go?

Hair follicle tests can generally detect drug use as far back as three months (90 days). In this way, hair follicle tests can be more useful than drug urinalysis, which only detects substance use for a maximum of 30 days. It doesn’t make a difference how long your hair is when it comes to the duration of time a hair follicle test can detect drug use—the maximum cutoff is 90 days either way.

Can a hair follicle test go back six months?

No, hair follicle tests cannot detect drug use that occured six months ago. The maximum window a hair follicle test can detect drug use is 90 days. Any drugs you used more than 90 days ago will not show up on a hair follicle drug screen.

Can a hair follicle test go back 12 months?

No, a hair follicle drug test will not be able to detect drugs you used 12 months ago even if you haven’t cut your hair in over a year. This type of drug testing only analyzes the bottom portion of your hair—the part that comes out of your scalp, and the maximum window of effectiveness for hair follicle drug tests is 90 days.

How much do hair follicle tests cost?

Hair follicle tests vary widely in terms of pricing. Some of the cheapest options may only cost $20 or less, but if you have your hair tested by an accredited lab, the process can cost $125 or even more. This price range is quite high compared to urinalysis, which generally only costs around $30 even when performed in a lab.

Hair follicle vs. urine drug testing

In addition to costing more, hair follicle drug testing can also detect the use of drugs for up to 90 days while urine drug testing is limited to a 30-day window. On the flipside, urinalysis often detects seven or even 12 different types of drugs while hair follicle testing is usually limited to a five-panel screen. 

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