Hair Drug Test Facts and FAQs

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General Hair Drug Test Facts

What is hair drug testing?

Hair testing analyzes drugs within the hair shaft, rather than body fluids like urine or saliva, to determine whether drugs of abuse are present. Compared to the analysis of body fluids, hair testing is highly resistant to evasion by adulterating or substituting samples or by simply abstaining from drug use for a few days. Psychemedics’ patented method for detecting drugs in hair uses proprietary immunoassay and state-of-the-art GC/MS/MS or LC/MS/MS confirmation to permanently measure the drug molecules and metabolites entrapped in hair, which were incorporated following ingestion. This technology offers significantly greater detection ability than other methods of analyzing hair or body fluids.

Who is using hair drug testing?

Thousands of corporations use Psychemedics’ tests to screen applicants and perform random drug tests on their employees. Schools have been using the Psychemedics test since 1997 to help their students stay drug-free. Courts routinely use Psychemedics’ test in their probation, parole, and diversionary programs. The use of hair is well established, and Psychemedics has been doing hair tests since 1987.

What drugs are included in a standard hair drug test?

Cocaine, marijuana, opiates (including heroin, codeine, morphine, oxycodone, oxymorphone, hydrocodone, and hydromorphone), methamphetamine, Ecstasy (MDMA), Eve (MDEA), and phencyclidine (PCP).

Does a Psychemedics hair test pull the hair out of the scalp to examine the follicle?

No.  Testing a hair follicle would require a painful collection process. The true hair follicle test requires the hair to be “pulled” out of the scalp. However, Psychemedics hair follicle test requires the smallest sample in the industry, snipping above the scalp. No hair is “pulled” out of the scalp, and the hair follicle is not disturbed. Sample collection is a completely painless, quick procedure.

What time period does a standard test cover?

A standard test of one-and-one-half inches of head hair cut close to the scalp can provide several months to detect drug ingestion.

How fast does head hair grow?

Studies indicate that hair collected at the head’s crown grows on an average of approximately 1.3 cm (or ½ inch) per month. This growth rate may vary among people; consequently, the same 3.9cm length of hair may represent slightly different time periods.

How does hair analysis compare to urinalysis?

The primary difference is the wider window of detection with hair. Cocaine, methamphetamine, opiates, and PCP are rapidly excreted and usually undetectable in urine 72 hours after use. Rather than the hours or days covered by a body fluid test, a hair test covers a period of months, ensuring that a drug user cannot evade the test by simply abstaining for a few days. Additional advantages include non-intrusive collection procedures, virtual elimination of test evasion through substitution or adulteration, and greater accuracy through test repetition capability. Combining an increased window of detection and resistance to evasion makes hair testing far more effective than urinalysis in correctly identifying drug users.

How soon after drug use can a drug be detected in hair?

It takes approximately 5-7 days from drug use to portion the hair containing that drug to grow above the scalp.

What is the shortest time period that can accurately be evaluated?

In most situations, the minimum time period is approximately one month. A hair test does not determine drugs used on a particular day or week.

How sensitive is hair testing in detecting drug users?

Comparison studies have proven that Psychemedics’ testing is up to 6-10 times more effective in identifying drug users than urinalysis. In other words, 85% of the drug users identified by a Psychemedics test could get through a urine screen and enter the workforce.

Is all hair testing alike?

No, Psychemedics uses its proprietary digestion method to remove virtually 100% of the hair’s drugs, thereby increasing detection capabilities. Other laboratories may leach the drug from the hair, leaving behind or destroying some of the drugs in the process. Psychemedics also employs an extensive wash procedure on test samples and analyzes the wash to ensure that any potential contamination has been removed or taken into account. Other labs may use a less effective wash and/or do not analyze the wash, putting their clients at risk for making employment decisions based on a result that may reflect external contamination.

How does Psychemedics establish its cut-off levels?

These levels are based on field studies that establish the presence of the drugs following ingestion. These levels are included in Psychemedics’ FDA submissions and are similar to the cut-off levels in the 2004 proposed SAMHSA mandatory guidelines.


How much hair is needed for a hair drug test?

Psychemedics’ standard screen, along with GC/MS/MS or LC/MS/MS confirmation, usually requires a cosmetically undetectable lock of hair preferably snipped from the back of the head, just below the crown. In general, the amount needed is the thickness of a shoelace tip. Hair analysis methods used by other laboratories may require significantly more hair.

Can hair drug tests be run on people with little or no hair?

Yes. Hair can be collected from several locations on the head and combined to obtain the required amount of hair. If head hair is not available, certain body hair can be used as an alternative.

Can hair collected from a brush be used?

No. For workplace drug testing, Psychemedics requires a hair sample to be collected using the proper chain-of-custody protocols to withstand a legal challenge. Psychemedics requires that the sample be submitted with Psychemedics Sample Acquisition Materials. The test subject must initial the sample to certify the sample’s authenticity at the time of collection.

How are collections performed on candidates that use artificial hairpieces or attachments to their own hair?

The collection process allows the collector only to take the candidate’s natural hair. Natural head hair or nape hair can be taken. Body hair can also be taken when hair from those two sources is not available.

Where do I get help regarding collection?

Psychemedics provides detailed instruction through a written training manual and video. Both are available in English and Spanish. Additional help is available through Client Service Managers dedicated to each client and from Psychemedics’ professional trainer.

Sample Characteristics

Does chemical treatment of the hair affect the test results?

Commonly used hair procedures (e.g., shampoos, conditioners, sprays, mousses, and gels) have no significant effect. In fact, normal hair washing helps to remove external contamination. Normal hair treatments such as bleaching, perming, and dyeing generally will not significantly lower the quantitative results. If the hair’s protein matrix has been damaged to the point of breaking (cortex damage), the level of the drug can be significantly affected. However, severely treated or damaged hair can be readily identified from the wash and/or staining procedures.

Is there a risk that the results of a hair test can be affected by environmental contamination?

Psychemedics utilizes several independent approaches that, in various combinations, rule out the possibility of a positive result from external contamination. The first method involves extensive chemical washing of the hair specimen before the screening, followed by an analysis of the wash’s content. This wash analysis is a critical step to ensure that any contamination is effectively accounted for. Additionally, Psychemedics measures the presence of metabolites. If drugs were in the air or on a person’s hands and thereby got on a person’s hair from outside, the drug would be present as the drug substance itself, not as certain metabolites or metabolite/parent drug ratios which are known to be produced by ingestion. Psychemedics’ ability to distinguish and measure metabolites with its highly sensitive GC/MS/MS or LC/MS/MS equipment is one criteria used to eliminate the possibility of false positives from external contamination. Any positive internal contamination (e.g., from passive inhalation or even poppy seed consumption) is distinguished from deliberate drug use by setting GC/MS/MS or LC/MS/MS cut-off levels above those which can be produced by passive internal exposure. Studies have shown that the combination of extensive washing, metabolite analysis, and proper cut-off levels is necessary to avoid false positives due to external contamination.

Laboratory Procedures

Does Psychemedics perform GC/MS/MS or LC/MS/MS confirmation of all positive results?

Psychemedics provides automatic confirmation for samples that screen positive.

What is done with the excess hair that is not tested?

The hair not used from the time period being tested, and all remaining hair is stored in the chain-of-custody sample acquisition pouch. Negative hair is stored for approximately 1 month. Positive hair is stored for two years.

How long are positive test result reports kept on file?

Laboratory records and test results are digitally stored indefinitely.

PDT-90 Personal Drug Testing Kit
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Parents can administer the test in the privacy of their own homes. Just collect a small sample of a child’s hair, send the sample to the Psychemedics laboratory and receive notification of the results within 3-5 business days of receipt of the sample at the laboratory. The ‘PDT-90’ includes all instructions plus a pre-paid mailing envelope for the sample. No names are used so complete confidentiality is assured.

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