What to Know About a Hair Follicle Drug Test

A hair follicle drug test is one way to screen for recreational drug use or prescription drug abuse. A section of hair, about 200 strands, is sent to a lab for testing.

One of the benefits of follicle drug tests is that they can show whether someone used or abused drugs as far back as three months before the test.

The test can pick up drugs or drug metabolites inside the hair shaft that have been deposited through the bloodstream. Like urine tests, the drugs that can be detected will vary depending on the chosen panel.

A standard five-panel test looks for:

• Cannabis
• Amphetamines, including MDMA (ecstasy) and MDEA (eve)
• Methamphetamine
• Cocaine
• Opioids, including heroin, fentanyl, codeine, and oxycodone
• Phencyclidine (PCP)

Read on for more information about hair follicle drug testing, how it’s done, and how accurate it is.

Why Is a Hair Follicle Drug Test Necessary?

Drug tests are used to show drug use or misuse. Follicle drug tests can be used in:

• Workplaces to screen applicants, periodically test employees, or test employees after an accident or other issue
• Forensic and legal testing, including during criminal investigations or child protection cases
• Drug rehabilitation programs to check for long-term drug use/abuse

How a Hair Follicle Drug Test Works

When a person uses drugs, they go into the bloodstream. Because each hair follicle has a blood vessel, drugs can travel through the bloodstream into the hair follicle. When the drug is processed (or metabolized) by a person's body, it creates byproducts called metabolites. These metabolites are found in the hair.

In a laboratory, a procedure called enzyme-linked immunosorbent assay (ELISA) is performed on the hair sample. The metabolites of a drug react to the test to show a positive, negative, or invalid response.

If the result is positive, a second test called gas chromatography–mass spectrometry (CG-MS) is performed to confirm the result. The CG-MS is a different method of testing for substances and can confirm a positive result from the ELISA test.

To do a hair follicle drug test, a hair sample is taken from the person’s head, close to the scalp. The sample must be 1.5 inches long and about as thick as a pencil, which is about 200 individual strands of hair. It is then sent to a lab for analysis.

The test can detect metabolites of drugs, which are substances made from the breakdown of drugs. It can detect drugs used within the past 90 days.

Home Hair Tests

At-home hair drug tests are available in stores and without a prescription. They involve collecting hair and then sending it to a lab for analysis.

How to Use a Home Hair Test

Using a home hair test is pretty straightforward. First, read the instruction manual so you know what to do. Take the hair sample necessary based on the directions and wrap it in the foil provided.

Then, mail the foil-wrapped hair in the container or envelope with the kit to the laboratory. It will then be analyzed. You can typically get the results by calling the phone number provided or going online and using the specific ID number that came with your kit.

Is a Home Hair Follicle Test Accurate?

Because home tests are sent to a lab, they're comparable to regular hair follicle drug tests. Neither type of test is 100% accurate, even though they go through a two-step process.

Understanding Hair Follicle Test Results

The results of the test will be reported as positive, negative, or inconclusive. Here's what those terms mean.

Negative

A negative result means no drugs or metabolites were found in the sample. It doesn’t mean the person hasn’t used any drugs, however.

The person could have used a drug very recently, before it showed up in the hair. Or, they might not have used enough of the drug to be detected. They could also have used other drugs for which the test didn't screen.

Positive

A positive result means the drug or metabolite was found in the hair sample. All laboratories have no standard positive cutoff values, which may vary among labs.

Certain foods and medications can cause false positives. Cold remedies, decongestants, and hay fever medicines can show up as amphetamines and poppy seeds may show up as opiates.

Inconclusive

An inconclusive result may mean the hair sample was contaminated or something went wrong with testing. You might be asked to provide another sample.

How Accurate Is a Hair Follicle Drug Test?

Hair follicle drug tests are very accurate in detecting long-term drug use because of the large window of time they can detect.

However, the test may not be able to detect if someone uses drugs very infrequently or uses drugs shortly before the test. Drug use takes about seven to 10 days to show up in the hair.

The accuracy statistics of hair follicle testing is also different for different substances. For example, studies have shown it to be superior to urine testing in detecting cocaine and opioids, but less reliable in detecting marijuana and alcohol.

Other factors may lead to inaccurate or biased results, including:

• Contaminated hair: Even if you don't use a drug like cocaine, being around it can cause cocaine molecules to bind to your hair. It may not be entirely removed with washing, leading to a false positive.
• Hair color: Some drug metabolites bind more easily to melanin in darker hair than lighter hair, which can lead to falsely high concentrations.
• Hair treatments: Shampooing, coloring, relaxing, and bleaching the hair can impact the metabolite concentration detected; in these cases, untreated hair from the body might be a better choice for testing.
  

Can a Hair Follicle Drug Test Identify Date of Drug Use?

No, it cannot identify the specific date of drug use. It can only show whether a substance has been used within the past 90 days.

How Much Does a Hair Follicle Drug Test Cost?

The cost of a hair follicle drug test can vary, depending on the kind of hair follicle test ordered (the number of drugs in a screen can differ), where you go for testing, and who ordered the test.

Your health insurance plan may cover the costs, or your employer may if they are ordering it. If you buy a home test, you pay for all the associated fees.

Many at-home tests will charge an extra fee for the laboratory analysis, adding to the total cost of the test. A 12-drug test from one of the industry leaders in hair follicle drug testing costs about $90, including laboratory fees. Other brands can cost less (though might not test for as many substances).

Hair Follicle Drug Test vs. Urine Drug Test

A urine drug test can only detect drug use for several days, while a hair follicle drug test can pick up on drug use for a longer period of time. Some urine tests provide instant results, but hair tests must be sent to a lab for completion.

Research has shown that urine testing can better pick up cannabis, heroin/opioids, benzodiazepines, and methadone, but hair drug tests are better at picking up cocaine. In one study researchers compared hair follicle drug test results in people who admitted their drug use, so they could verify the test gave a positive result.

In people who did not admit to drug use, urine testing was more effective at picking up cannabis and benzodiazepines, and hair testing was better at detecting cocaine and oxycodone.

What if I Have No Hair?

A body hair sample can be collected if someone has no hair on their head. It should be noted, though, that body hair tests can detect drugs used over a more extended period because the hair grows more slowly.

Summary

While most people may be familiar with urine screening drug tests, hair follicle drug tests are also used, although less widely.

Whereas urine drug tests can detect recent drug use, hair follicle drug tests have a much larger window of detection. This allows persistent drug use to be detected along with more isolated instances of drug use.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

1. Gryczynski J, Schwartz RP, Mitchell SG, O'Grady KE, Ondersma SJ. Hair drug testing results and self-reported drug use among primary care patients with moderate-risk illicit drug use. Drug Alcohol Depend. 2014;141:44-50. doi:10.1016/j.drugalcdep.2014.05.001
2. Usman M, Naseer A, Baig Y, et al. Forensic toxicological analysis of hair: a review. Egypt J Forensic Sci. 9, 17 (2019). doi:10.1186/s41935-019-0119-5
3. Koster RA, Alffenaar JW, Greijdanus B, VanDernagel JE, Uges DR. Fast and highly selective LC-MS/MS screening for THC and 16 other abused drugs and metabolites in human hair to monitor patients for drug abuse. Ther Drug Monit. 2014;36(2):234-243. doi:10.1097/FTD.0b013e3182a377e8
4. Palamar JJ, Le A, Guarino H, Mateu-Gelabert P. A comparison of the utility of urine- and hair testing in detecting self-reported drug use among young adult opioid users. Drug Alcohol Depend. 2019;200:161-167. doi:10.1016/j.drugalcdep.2019.04.008
5. Paul R, Williams R, Hodson V, Peake C. Detection of cannabinoids in hair after cosmetic application of hemp oil. Sci Rep. 2019;9:2582. doi:10.1038/s41598-019-39609-0
6. Sharma G, Oden N, VanVeldhuisen PC, Bogenschutz MP. Hair analysis and its concordance with self-report for drug users presenting in emergency department. Drug Alcohol Depend. 2016;167:149-155. doi:10.1016/j.drugalcdep.2016.08.007
7. Substance Abuse and Mental Health Services Administration. Clinical Drug Testing in Primary Care.
8. Palamar JJ, Salomone A. On the challenges of hair testing to detect underreported substance use in research settings. The American Journal of Drug and Alcohol Abuse. 2023;49(1):1-4.10.1080/00952990.2023.2166414
9. Palamar JJ, Le A, Guarino H, Mateu-Gelabert P. A comparison of the utility of urine and hair testing in detecting self-reported drug use among young adult opioid users.Drug and Alcohol Dependence. 2019;200:161-167. doi:10.1016/j.drugalcdep.2019.04.008

By Jaime R. Herndon, MS, MPH
Herndon is a freelance health/medical writer with a graduate certificate in science writing from Johns Hopkins University.

• Meet Our Medical Expert Board
• About Us
• Editorial Process
• Diversity Pledge
• Privacy Policy
• In the News
• Advertise
• Terms of Service
• Careers
• Contact
• EU Privacy

Verywell Health's content is for informational and educational purposes only. Our website is not intended to be a substitute for professional medical advice, diagnosis, or treatment.

We Care About Your Privacy

We and our 100 partners store and/or access information on a device, such as unique IDs in cookies to process personal data. You may accept or manage your choices by clicking below, including your right to object where legitimate interest is used, or at any time in the privacy policy page. These choices will be signaled to our partners and will not affect browsing data.

We and our partners process data to provide:

Store and/or access information on a device. Use limited data to select advertising. Create profiles for personalised advertising. Use profiles to select personalised advertising. Create profiles to personalise content. Use profiles to select personalised content. Measure advertising performance. Measure content performance. Understand audiences through statistics or combinations of data from different sources. Develop and improve services. Use limited data to select content. List of Partners (vendors)