How accurate is the hair follicle drug test?

Last Updated December 20th, 2021

Hair Follicle Test: Quick Facts

  • Detection window of up to 90 days.
  • Cannot be masked by the use of shampoos as the drug metabolites are a part of your hair.
  • High specificity across all drugs (around 90%)

Drugs in the Workplace

“Drug” does not rhyme with “work”. Drugs have been known to make you lax, take you to a “feel-good” place where everything seems to be working for you, except work itself. So if your employer is worried about your performance, he/she can order a drug test. It is justified in most instances and even federal law finds no qualms with it.

General effects of drugs in the workplace

  • The use of drugs can lead to poor morale and productivity in the workplace.
  • It is also known to affect the attendance of the employee and leads to greater absenteeism.
  • It can also lead to an inability to follow instructions and a lack of concentration
  • It can alter the physical appearance of the employee with eyes that are watery or blood- shot, along with the pupils of the eyes getting larger or smaller.

Why employers drug test?

Employers drug test to ensure that it:

  • Deters employees from drug abuse in the present and the future
  • Prevents the hiring of candidates involved in irregular or regular abuse of drugs
  • Helps employees who are currently using drugs to avoid them and recover healthily
  • Provides a safe environment for all employees
  • Assures consumers that employees are working in a safe environment
  • Helps the company comply with state and federal regulations

Access to drug test results

Drug test results are generally considered personal health information. This means that an employee may be required to sign an agreement indicating consent so that the employer can then view the results of the drug test. For information about the issues that are related to the release of health information the employer must contact the respective state’s department of health and social services. The Health Insurance Portability and Accountability Act (HIPAA) dictates under what conditions and to whom sensitive health information may be released.

Grounds of Drug Testing at the Workplace

Pre-employment: An employer, in accordance with company policy, may test a candidate for substance abuse before he/she joins the company

Periodic: A periodic screening of employees is done in many companies. These tests are generally scheduled once in a year. A combination of tests may be used depending upon how often the tests are carried out. Since this kind of testing is usually announced, more employees are generally comfortable going in for this test

Random: Random testing of employees may be carried out to present as a deterrent to drug abuse in the company. For this purpose, generally, the subjects are picked at random and the test is also unannounced so as to help identify infrequent users of drugs.

Reasonable suspicion: If a supervisor documents observable signs and symptoms of drug use for an employee, then he/she may recommend drug testing. However, in such a case it is necessary to clearly define what behavior or symptoms qualify for testing for substance abuse. Also, the observations made by the supervisor must be corroborated by another supervisor. Supervisor training is also necessary.

The legality of Drug Testing

There is no federal law prohibiting employers from the drug testing of employees even on a random basis. However, there may be state laws that safeguard the privacy of the employee and may actually prevent the employer from drug testing employees on a random basis, especially those with no reported history of drug abuse or those not in safety-sensitive positions of employment. Also, the ADA (Americans with Disabilities Act) does not allow the drug testing of employees who are currently undergoing rehabilitation or have completed rehabilitation and are not currently indulging in substance abuse.

Hair Follicle Test: An easy test for drugs

Even if you smoke up or inhale drugs or inject yourself with them only occasionally, you might still test positive in a hair follicle drug screening test. In the hair follicle test, about 100 to 120 strands of hair are taken. They are cut with scissors and are taken to the lab immediately for testing. Another important thing to remember here is that the hair follicle test not only tests for illicit drugs but also for misuse of prescription medication.

Method of Screening

In the hair follicle test, the hair strands are taken from the crown of the head. They are taken from different regions of the crown to avoid creating a bald spot. If the person has little or no hair, it is possible that the hair used for testing will be obtained from another part of the body. The cut hair is placed by the collected in a foil which is placed in a sealed envelope, and then the envelope is sent for testing. In order to prevent contamination of the hair sample the interviewer generally wears a head cap and uses a sterilized pair of scissors.

Understanding your test results

A negative result means that you have not taken any drugs in the past 90 days (for a 1.5-inch sample). The first round of drug testing involves the use of ELISA (enzyme-linked immunosorbent assay) and it will take 24 hours for the results to come back. If the test results are positive, then further tests will need to be done.

A positive result means that the samples need to undergo a second test. A gas chromatography/mass spectrometry test is used in the second step to confirm the results. The whole process of confirming a positive result will take up to 72 hours.

A test may also be inconclusive. Sometimes, the sample may not be of sufficient quality to arrive at a result. This may be due to incorrect sampling at the time of collection of the hair. In such cases, the subject will be requested to return for another appointment.

Drugs Screened by the Hair Follicle Test

The hair follicle test tests for the following drugs:

  • Amphetamine
  • Methamphetamine
  • Cocaine
  • Phencyclidine (PCP)
  • Ecstasy
  • Opioids (Like codeine and morphine)

Advantages of a Hair Follicle Test

The hair follicle test has several advantages:

  • The hair follicle test has an extended window of detection. The time frame is about a month for every half inch of hair. This means that a 1.5-inch strand of hair would represent a 90-day window. This means that it can catch even occasional or intermittent users. This is something a urine drug test cannot do.
  • It also doesn’t require any special means for storing the hair. It could be stored anywhere in a foil within a sealed envelope and there is no risk of spoilage.
  • Being a hair strand and not fluid, there is no risk of spillage and transportation is easy.
  • Washing or dyeing of the hair also does not affect your test results.
  • It is less intrusive and easier than obtaining a urine sample for drug testing.

How much does a hair drug test cost?

A hair follicle drug test costs approximately anywhere between $100 and $125 in the United States for each subject. This would also depend, though, upon the testing conditions (number of panels, the purpose of testing, and who is mandating the test).

Limitations of hair follicle testing

There are a few limitations in using hair follicles for drug screening. Some of them are:

  • Cost: The cost associated with a hair drug test is very high, about $100 or more for each person.
  • Consistency: It is difficult to obtain hair of the same length from several different patients also if they have to come from the same part of the body.
  • Inadequacy: Sometimes the samples obtained may be inadequate for certain subjects to arrive at an accurate analysis.
  • Cosmetic concern: The participants’ cosmetic concerns must also be taken into account.
  • Environmental contamination: Contaminants in the environment are known to alter the test, even with the washing of hair prior to testing.
  • Accuracy of hair drug tests is not established: A 2017 studyfound that the self-reporting of cannabis use and the results of the hair drug tests did not match. This may indicate the potential of a false positive.

Hair Drug Tests versus Urine Drug Tests

A urine drug test generally has a detection window of a little over three days. A hair drug test, on the other hand, has a detection window of about 90 days. This is because drug metabolites present in the bloodstream become a part of the hair. They are also transferred from the sweat and the sebum onto the scalp. But this process takes at least 5 to 6 days after intake of the drug. This means that recent instances of drug use cannot be detected by hair drug tests.

So, analysis of the urine is better for detecting recent drug use. But a hair drug test may help detect infrequent drug use from as far back as three months. This means that in a corporate scenario the urine drug test works better for a specific incident at the workplace. A hair drug test works better at the screening of those taking interviews or for understanding the drug use patterns of long-term employees. Sometimes a combination of both urine and hair drug tests may be used.

Alternatives to a hair follicle drug test

The other methods of screening for drugs involve:

Blood Tests

Blood tests are useful in analyzing the immediate use of drugs. The drug metabolites do not remain in the blood for long (< 1 day generally) and are then passed into the urine. Also, a blood test is sometimes the only way to detect drug abuse. Another point to be noted here is that unlike blood tests for alcohol, the blood test for drugs does not indicate a level of intoxication or impairment in the test subject.

Saliva Tests

The test of oral fluids for the presence of drugs holds great promise in detecting current use and impairment. This is the easiest way to obtain a sample for drug testing as it only involves taking a swab from the mouth of the subject. Also, the drugs stay in the saliva only for a short duration. They are passed into the urine soon after. So even though the detection window is shorter. However, the sensitivity of the test is higher as compared to other tests in the case of marijuana, amphetamines, and methamphetamines. It is also harder to adulterate or substitute for.

Do hair follicle tests really help?

Hair drug tests are preferred at workplaces for drug detection due to the ease of obtaining a sample and the longer detection window. If you are worried about a hair drug test, understand that it is not very reliable and might give an incorrect result. A negative result does not always mean that you are into substance abuse. This is why companies generally use a combination of self-reporting methods, statistical analysis, and laboratory drug tests to ensure accuracy.


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