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Hair Drug Testing, The Facts for Employers

Hair testing provides a 90-day detection window for repetitive drug use patterns, helping to identify habitual and periodic drug use. It is a hard test to cheat and often yields higher positivity rates when compared to urine or oral fluid testing.

What drugs are tested in a hair test?

The most common types of testing, which is used by many Oil/Gas and other plants, are amphetamines (amphetamine, methamphetamine, MDMA and MDA), cocaine, marijuana, opiates, oxycodones, and PCP. DISA drug tests are often for this, but they may add other drugs as well. Our drug tests can test for up to 17 different sets of drugs and alcohol.

When should a company choose a hair drug test?

A hair test is an excellent option for pre-employment and random testing programs. Because hair testing detects a pattern of repetitive drug use over a longer period, usually up to 90 days, it is not well-suited for situations when a drug test result is needed as close as possible to the time an incident occurs.

How is a hair drug test collected?

Our trained collectors at Fastest Labs of Webster cut approximately 100-120 strands of hair from the crown of the donor’s head. The hair is cut as close to the scalp as possible, so only the strands of hair above the scalp are tested and not the actual hair follicle. We take our time when doing this type of testing and do everything possible to avoid leaving a visible spot on the head.

Can products and treatments affect a hair drug test result?

We have not found any adulterants that can beat a hair drug test at this time:

  • When shampoos, sprays or gels were applied to cut hair samples, they had little or no effect on positive or negative hair specimens.
  • When normal hair treatments, including bleaching or dyeing, were applied to cut hair samples, they typically did not interfere with test results.
  • When tested under worst-case scenario conditions, most treatments had minimal or no impact on test results for the majority of drugs. When there was an effect, screening absorbance readings became more negative for positive hair specimens, and slightly more negative for the negative samples.

Can you cheat a hair drug test?

Hair testing collections are observed, meaning a collection can only be performed at a collection site, and performed by a collector, therefore reducing the likelihood of tampering or adulteration by a donor.

What if the subject does not have head hair?

We can choose to take body hair instead. Hair from the underarm, chest, arms and legs are suitable for drug testing. However many people do not realize that since body hair grows differently than head hair the detection period for body hair may be greater than 90 days.

What if the subject comes in without head or body hair?

We get calls all the time about people who shave their bodies, or wear their hair short, or both. We advise them that if they are scheduled for a hair test and arrive without enough sample to collect it can be considered a refusal to test, which their company may choose to assume is a failed test. We also advise that we may call their company to see if they want to do a fingernail drug test instead.

Is there a difference between hair drug testing and hair follicle drug testing?

Yes, calling a hair drug test a hair follicle drug test is a common misconception. During a hair drug test collection, the hair is cut as close to the scalp as possible, only the hair above the scalp is tested, not the follicle. Generally, follicles are only used in cases of DNA or Genetic testing.


Hair testing is great for all types of employers and especially companies that have employees in safety-sensitive positions. Hair testing helps to mitigate risk and increase workplace safety