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Guide To Hair Follicle Drug Tests

Drug testing can be an important component of pre-employment screening. Among the various methodologies available for drug detection, a hair follicle drug test offers unique benefits for employers who need to assess historic drug use. The test is non-invasive and provides a comprehensive overview of an individual’s substance use within a 90-day timeframe.

This guide presents an in-depth look at hair follicle drug testing, its importance for employers, and how it compares to other testing methods like urine drug tests, saliva drug tests, and blood tests. We’ll also cover how hair testing works, its detection period, and relevant hair follicle drug testing laws that employers should be aware of before implementing drug testing for job candidates or employees. 

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What Is A Hair Follicle Drug Test?

A hair follicle drug test, also known as a hair drug test, is a technique used to detect the presence of specific drugs in an individual’s system. This test analyzes a small sample of hair from close to the scalp to determine drug use within a 90-day timeframe.

Hair drug testing involves a two-step methodology. It begins with a preliminary screening test, and if the results indicate drug usage, a confirmatory test is subsequently performed. This method is notable for its ability to provide a comprehensive overview of the individual’s recent substance use history and its high resistance to tampering.

Why Is Hair Follicle Drug Testing Important?

A pre-employment hair follicle test can contribute additional data to the background check process. Because hair drug testing has a broad detection range, it can provide a more detailed snapshot of a candidate’s substance use patterns than other drug tests. 

By understanding an individual’s past substance use, employers can gain a fuller picture of their potential hires or even current employee drug use. This information becomes an invaluable tool for roles requiring alertness, focus, and safety. Drug tests for new and current employees may also be required by law for certain industries or positions, and conducting them can help employers stay compliant with local, state, or federal regulations.

How common are hair drug tests for employment? It depends on the industry and the professional role. Industries like transportation, construction, and other safety-sensitive lines of work may be most likely to find this type of test valuable for making informed hiring decisions.

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Hair Follicle vs. Urine vs. Blood Drug Tests

Employers have several drug testing options available to them, each with its own benefits. Key among these are hair follicle, urine, and blood drug tests. The hair drug test offers the longest window of detection, with the ability to identify drug use up to 90 days prior. Urine drug tests, on the other hand, have a shorter detection period, typically a few days to a week. Blood tests are more invasive, but they’re also more resistant to manipulation and can provide an accurate snapshot of current substance use. 

To compare these options in more detail, let’s look at the key differentiators between a hair vs. urine drug test and a hair test vs. blood test.

Hair Follicle TestUrine TestBlood Test
Detection WindowUp to 90 daysFew days to a weekFew hours to a few days
Substance DetectionComprehensiveModerateCurrent substance use
Tamper ResistanceHighLowHigh

Hair follicle tests provide a much broader window for detection than either urine or blood tests. These tests can glean a detailed substance usage pattern over an extended time and are most often run by employers in industries requiring a high level of alertness. Such industries may include construction, manufacturing, trucking and transportation, and oil and gas production.

In contrast, urine and blood tests provide a look into an individual’s most recent drug use. They can be ideal in environments where the focus is more immediate substance use rather than historical patterns. Industries that may rely on urine or blood drug tests include education, social work, healthcare, law enforcement, and government positions.  

How Does Hair Follicle Drug Testing Work?

A hair follicle drug test begins with collecting a small sample of hair from close to the scalp, usually facilitated by a technician in a drug testing facility or medical office. The collected hair sample is then sent to a certified lab for testing.

Even though these tests are commonly referred to as “hair follicle tests,” hair follicles are not used in the test and hair does not need to be plucked to be tested.  Instead, a sample of strands of hair are cut or shaved and those strands are tested.

At the laboratory, a two-step process occurs. The first is an initial immunoassay screening test. If the hair sample tests positive during this screening, a second test is performed. This test, which uses advanced techniques like gas or liquid chromatography and mass spectrometry, provides a more detailed analysis. This analysis can confirm the presence of drugs and also identify specific substances.

Do You Use Body Hair or Head Hair for Hair Drug Tests?

For a hair follicle drug test, hair is usually collected from the head. About 90-120 strands are needed, a bunch approximately the thickness of a pencil. If head hair is too short or not available, body hair can be used instead. Hair is typically cut or shaved close to the skin to ensure the newest growth is collected. 

Strands of head hair should be at least 1 ½ inches long to provide a 90-day drug history. Because body hair grows more slowly than head hair, when body hair is used, tests may provide a usage history significantly longer than 90 days. 

What Drugs Show Up in a Hair Test?

Hair follicle drug testing provides a broad spectrum of drug detection, encompassing a substantial list of commonly abused substances. The most frequently tested substances in a standard hair follicle drug test include 

  • Marijuana (THC) 
  • Cocaine 
  • Amphetamines (such as methamphetamine or MDMA/Ecstasy) 
  • Opiates (including codeine, morphine, and 6-acetylmorphine)
  • Phencyclidine (PCP)

How Far Back Do Hair Drug Tests Go?

Hair follicle tests have a detection window extending up to 90 days, a duration considerably longer than most other testing methods. The lengthy detection window of a hair drug test is attributed to the nature of hair growth and how drugs are incorporated into strands of hair.

After drug use, substances enter the bloodstream and circulate throughout the body. As hair grows, it absorbs blood carrying these substances, and the drug metabolites become trapped in the structure of the hair strand. Given the average rate of hair growth (about half an inch per month), a 1 ½ inch hair sample can provide a 3-month history of drug use. 

How Much Does a Hair Follicle Test Cost?

The cost of a hair follicle drug test can vary widely based on several factors, but generally, pricing for clinic–based drug testing usually starts at about $60. More invasive tests like hair drug tests may have a higher associated cost. The price can also increase for tests that include a higher number of panels (substances), such as a 10-panel drug test. This cost of hair tests can be on the higher end compared to other drug testing methods. However, employers may find the additional cost of hair testing worthwhile, considering the broader detection window and the method’s resistance to manipulation.

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Hair Follicle Drug Testing Laws To Know

Specific pre-employment drug testing laws govern how, when, and why employers may conduct drug screenings, including hair follicle testing. Laws may vary from jurisdiction to jurisdiction, so it’s crucial to be aware of federal, state, and local rules applicable to your location and where you’re hiring.

  • Fair Credit Reporting Act (FCRA): If employers use a third-party agency to conduct a hair follicle drug test for employment purposes, they must follow FCRA guidelines. This includes providing written notice of their intent to conduct a drug testing, obtaining written consent from candidates and/or employees before proceeding, and following the adverse action process if the test results may negatively impact a hiring decision.
  • Americans with Disabilities Act (ADA): This federal law stipulates that employers cannot discriminate against employees that have substance use disorders who are in recovery and not currently engaging in the use of drugs. Employers must provide reasonable accommodations, including potential adjustments to work schedules or duties, to support these employees.
  • State and local laws: Depending on their specific location, employers may have to comply with specific state and local laws regulating drug testing. For example, in some jurisdictions, employers must extend a conditional job offer before conducting a drug screening. Employers should seek out information on any state or county drug testing regulations before ordering tests.
  • Marijuana laws: The legal landscape for marijuana is evolving, with many states either legalizing or decriminalizing its use, which impacts workplace drug testing. For example, in certain states, employers may not make employment decisions based on marijuana use. Taking this a step further, several states—including Washington, California, New York, New Jersey, Rhode Island, Connecticut, and Montana—have prohibited pre-employment testing for marijuana. Employers should consider the legal implications of their drug testing policies, including hair follicle testing, as they navigate this complex regulatory environment.

Industry-specific regulations: Certain industries, especially those classified as safety-sensitive, are subject to specific standards regarding drug testing. Hair testing may be restricted in some cases, in favor of oral or fluid specimens, such as for roles within the US Department of Transportation.

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Drug testing is a valuable tool for employers, helping you make informed hiring choices and foster a secure workplace while minimizing potential risks. Collaborating with an employment screening partner such as GoodHire can enhance your ability to efficiently manage the background check process, including drug tests, and help ensure compliance. With a range of employment drug testing solutions—including hair follicle drug tests—GoodHire provides quick, precise test outcomes verified by a Medical Review Officer. Get started today.

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The resources provided here are for educational purposes only and do not constitute legal advice. We advise you to consult your own counsel if you have legal questions related to your specific practices and compliance with applicable laws.

About the Author

As GoodHire’s managing editor, Sara Korolevich produces educational resources for employers on a variety of employment screening topics, including compliance and screening best practices, and writes about GoodHire’s company and product news. Sara’s experience stems from 20+ years working as a B2C and B2B PR and communications professional.