A hair follicle drug test, also known as a hair drug test, screens for illicit drug use and the misuse of prescription medication. During this test, a small amount of hair is removed from your head using scissors. The sample is then analyzed for signs of drug use during the 90 days preceding the test. It’s typically used to test for:

While a urine drug screen can detect if you’ve used drugs in the last few days, a hair follicle drug test can detect drug use in the past 90 days.

Your workplace may request a hair follicle test to screen for illicit drug use before hire or randomly during employment. Some research also indicates that hair drug testing can be useful for monitoring drug use in at-risk individuals when used alongside self-reporting.

Your hair follicle test might take place in a lab or within a hospital setting. Or your workplace may perform the test using a kit that’s then mailed to a laboratory. You can also order at-home hair follicle tests online.

If your workplace has mandated that you take the test, they’ll likely require you to be supervised during the testing process.

You can wash your hair, dye your hair, and use styling products without affecting the accuracy of the test.

After confirming identifying information, the collector will cut between 100 and 120 hairs from the crown of your head. They can collect the hairs from different spots on your crown to avoid creating a bald spot.

If you have very little or no hair on your head, the collector might use body hair for the test instead. The collector will place the hair in foil and then in a secure envelope to be mailed for overnight testing.

A negative result can be determined within 24 hours of hair removal. A test called ELISA is used as a screening test. This test determines if the hair sample is negative for drug use. A negative result indicates that you haven’t engaged in illicit drug use over the past 90 days. Additional testing is required to confirm a positive result.

A positive drug test is confirmed after 72 hours. All nonnegative tests undergo a second test, called gas chromatography/mass spectrometry (GC/MS). It confirms a positive test result. This test also identifies the specific drugs used.

An inconclusive result isn’t common when testing procedures are followed. In some cases, improper collection of the hair specimen may result in the test being rejected completely. In this case, the test may be repeated.

The laboratory responsible for testing will deliver the results to the individual or organization requesting the test. They’ll use confidential means, like a secure fax, a phone call, or an online interface to share test results. Because lab results are confidential health information, you’ll need to sign a release before the results are passed on to your workplace.

Can the test identify the date of drug use?

A hair drug test detects a pattern of repeated drug use over the last 90 days. Because hair growth rates vary from person to person, this test can’t accurately determine when in the 90 days drugs were used.

The collection and testing of hair for this test follows a very specific set of standards to increase accuracy. During testing, the collected hair is washed and tested for environmental contamination that could change the results of the test. Your results won’t be affected if you wash your hair, dye your hair, or use styling products.

To guard against a false positive, laboratories conduct two tests. The first, called ELISA, is able to deliver a negative or positive result within 24 hours. The second, called GC/MS, is a widely accepted method for confirming a positive result. This second test can also test for specific drugs and can detect as many as 17 different drugs. The GC/MS also guards against false-positive results caused by foods like poppy seeds or hemp seeds.

One 2017 study did find inconsistency between self-reporting of cannabis use and the results of hair drug tests. This may indicate the potential of a false positive.

Certain medications may influence the results of the test. If a doctor has prescribed an opioid painkiller and you use them as directed, these drugs will show up on your test. In this case, your employer will likely request you provide documentation of prescriptions.

If you believe your hair drug test results are inaccurate, you may immediately request a retest from your employer.

A hair drug test is more expensive than a urine drug test. An at-home kits costs between $64.95 and $85. Drug tests performed in a hospital or laboratory may cost between $100 and $125.

If you’re a current employee and your workplace requires you to take a hair follicle drug test, they’re required by law to pay you for the time spent taking the test. They’ll also pay for the test itself.

If a drug test is part of pre-employment screening, the employer isn’t required to compensate you for your time.

Many insurance carriers cover drug tests if it’s performed within a hospital for medical purposes, like an inpatient stay or an emergency room visit.

The main difference between a hair follicle drug test and a urine drug test is the window of detection.

A urine drug test is used to test for drug use over the three days preceding the test. A hair follicle drug test is the only drug test that can detect repeated drug use up to 90 days prior to the test.

This is possible because drugs present in the bloodstream actually become a part of hair cells as the hair grows. The sweat and sebum present on your scalp may also play a role in drug presence in existing strands of hair.

Because of the rate of hair growth, drugs can’t be detected in the hair until five to seven days after use. In the case of a workplace accident, a hair drug test wouldn’t be an appropriate test for detecting recent drug use.

If you have questions or concerns about your drug test results, reach out to the medical review officer, or MRO. An MRO evaluates drug test results and may be able to explain your test results.

Hair follicle drug tests can identify drug use up to 90 days prior to the test date. That’s because the chemicals from the drugs that end up in your bloodstream become part of the hair cells as your hair grows.

Hair follicle drugs tests may not be appropriate for determining recent drug use. That’s because it may take five to seven days for the drugs to be identifiable through a hair follicle test. Urine drugs tests are used to detect recent drug use.

If you’re taking prescribed medications, let the administrator of the test know. Medications may lead to a false-positive test result.

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