Hair drug testing for court

A hair drug test for court, also known as a hair strand test or a hair follicle test, involves analysing samples of head hair or body hair for the presence of drugs and their metabolites.

In this article, we take a closer look at hair drug testing, including how the test works, the difference between head hair drug testing and body hair drug testing, and the ways that people try to cheat hair drug tests.

Table of contents

What is a hair drug test?

A hair drug test, also known as a hair strand test or a hair follicle test, involves analysing samples of head hair or body hair for the presence of drugs and their metabolites.

When a person consumes drugs, they are passed into the bloodstream, and the parent drug and a proportion of the drug’s metabolites enter the hair follicle.

When the hair is subjected to analysis at the toxicology laboratory the parent drug and its metabolites can be identified within the hair.

How does testing head hair for drugs work?

Hair drug testing works by analysing a cut hair sample for the presence of drugs and their metabolites.

When a person consumes drugs, they are broken down by the liver, and a proportion of the parent drug and its metabolites are absorbed into the bloodstream.

These drugs then enter the hair follicle and become trapped in the medulla, the innermost layer of the hair shaft, making it possible to detect them during analysis at the toxicology laboratory.

It takes approximately 7-10 days for the hair containing the drugs to grow above the surface of the scalp, and two weeks for this hair to be included in a cut sample.

The rate at which head hair grows enables us to determine a pattern of drug use over a defined period, depending on the length of hair selected (1cm of hair = one month of growth).

There are two methods available for head hair drug testing: segmented analysis or overview analysis.

Segmented analysis is the most detailed form of hair strand testing for drugs. This involves segmenting the hair into 1cm sections, for a month-by-month profile and therefore, a more detailed history of drug use.

This method is useful if you need to identify a trend in drug use, such as an increase or decrease over time, or to highlight intermittent use.

Segmented analysis can be used to identify patterns in drug use for a period of up to 12 months. The table below demonstrates how segmented analysis can be used, and how many segments of hair would be required depending on the period being tested.

Segmented analysis required (months) Number of segments (1cm per segment) Reported time period
1 1 1 month
3 3 3 individual months
6 6 6 individual months
9 9 9 individual months
12 12 12 individual months

Overview analysis is beneficial if you are looking to obtain a more general insight into a person’s drug use.This is because any episodes of drug use are averaged out over the period being tested.

The maximum length of hair that can be tested to provide an overview of drug use is 3cms, which provides an overview of three months.

The maximum overview period that can be provided is 12 months. However, this would be reported as 4 x 3-month overviews, rather than one 12-month overview.

The below table shows the options available for hair drug testing using overview analysis, and what will be shown in the report, depending on the required overview period:

Overview analysis required (months) Number of segments (3cm per segment) Reported time period
3 1 3 months
6 2 2 x 3-month periods
9 3 3 x 3-month periods
12 4 4 x 3-month periods

An important factor to bear in mind about overview hair drug testing, is that if an individual has not taken drugs for two months, but then takes an excessive quantity in one month, a hair follicle or hair strand drug test using overview analysis will find drug markers within the hair sample.

Unlike with segmented analysis, it is not possible to specify in which month the drugs are likely to have been consumed; only whether drug markers are present within the sample for that period.

How does testing body hair for drugs work?

If head hair is not available for drug testing, a sample of body hair can be collected instead, from the underarm, chest, leg, or face.

However, unlike head hair, body hair cannot be segmented to provide a month-by-month profile.

This is because the growth rate of body hair differs from head hair and is not consistent, meaning that a sample of body hair can only be used to provide a 12-month overview of drug use.

When a person consumes drugs, they are broken down by the liver, and a proportion of the parent drug and its metabolites are absorbed into the bloodstream.

As is the case with head hair, these drugs then enter the hair follicle and become trapped in the medulla, the innermost layer of the hair shaft, making it possible to detect them during analysis at the toxicology laboratory.

Unlike head hair, body hair samples are collected by weight, rather than the length of the hair strand.

When is a hair drug test performed?

Hair drug testing is the gold standard in toxicological analysis and is routinely used in the forensic and family law fields.

Hair drug testing is performed for a variety of reasons, from helping authorities make crucial decisions about a child’s welfare, to family courts handling custody disputes, and employers monitoring drug misuse in the workplace.

How is a sample collected for hair strand testing?

Samples for legally-instructed hair drug testing are usually collected by a trained sample collector, under chain of custody conditions, ensuring the samples are collected from the right people, and preventing sample tampering.

The hair sample needs to be cut from the highest point of the scalp (the vertex) as this region is associated with the least variation in growth rates.

Ideally, the sample needs to contain around 200 individual strands and should always be taken from a discreet area if possible.

Hair samples are usually taken from a person’s head. However, if head hair is not available, body hair can be collected from the underarm, leg, chest, or face.

 

How are drugs detected in a hair sample?

When a person consumes drugs, they are broken down by the liver, and a proportion of the parent drug and its metabolites are absorbed into the bloodstream.

These drugs then enter the hair follicle and become trapped in the medulla, the innermost layer of the hair shaft, making it possible to detect them during analysis at the toxicology laboratory.

Once the hair samples have been collected, and safely transported to the laboratory under chain of custody, testing and analysis can begin.

The first task at the laboratory is to chemically wash the hair samples three times, to remove or reduce any drug present on the surface of the hair prior to analysis.

This is because if someone has been in an environment heavily laden with a drug, detectable levels from smoke could be found on the outside of the hair sample. Drugs can also be transferred onto the hair by direct contact, such as by hands.

The washing solution can also be analysed if required. For example, if an individual admits to being surrounded by cannabis smokers, the washing solution could be used to back up the test results. Any external exposure to drugs should be declared at the time of sample collection.

When testing the hair for drugs, AlphaBiolabs follows the Society of Hair Testing guidelines for cut-off levels (where applicable) for hair sample types.

 

What can a hair drug test show and what can’t it show?

A hair drug test or hair follicle test can tell us which drugs are likely to have been consumed during the period prior to samples being collected, but no drug test can tell us:

The exact date, time, and method of ingestion

Laboratory testing can only tell us whether drugs are present in the sample during the period for which we are testing – not the exact date or time of day when they were taken.

There is also no way to tell how a substance was ingested using laboratory analysis.

Quantities that were consumed

Because of the way drugs are broken down by the body – with the parent drug and only a proportion of its metabolites excreted – it is impossible to determine exactly how much of a substance was taken prior to sample collection.

Whether hair treatments have impacted the results

Hair treatments including bleaching, perming, dyeing and excessive straightening have the potential to affect the results of a head hair drug test.

For this reason, we will also ask for full disclosure of any recent hair treatments so that this can be taken into consideration when preparing the results.

However, it is not possible to specifically determine to what extent such treatments may have impacted the results e.g. whether the amount of drugs in the hair has been lessened by these treatments.

 

Which drugs can be detected using hair drug testing?

The following drugs are the main drugs we test for in hair at AlphaBiolabs:  

Are there different types of hair drug test?

There are two types of hair drug test available: segmented analysis and overview analysis.

Segmented analysis is the most detailed form of hair strand testing for drugs. This involves segmenting the hair into 1cm sections, for a month-by-month profile and therefore, a more detailed history of drug use.

This method is useful if you need to identify a trend in drug use, such as an increase or decrease over time, or to highlight intermittent use.

Segmented analysis can be used to identify patterns in drug use for a period of up to 12 months.

Overview analysis is beneficial if you are looking to obtain a more general insight into a person’s drug use.

This is because any episodes of drug use are averaged out over the period being tested.

The maximum length of hair that can be tested to provide an overview of drug use is 3cms, which provides an overview of three months.

The maximum overview period that can be provided is 12 months. However, this would be reported as 4 x 3-month overviews.

However, if an individual has not taken drugs for two months, but then takes an excessive quantity in one month, a hair follicle or hair strand drug test using overview analysis will find drug markers within the hair sample.

Unlike with segmented analysis, it is not possible to specify in which month the drugs are likely to have been consumed. Only whether drug markers are present within the sample for that period.

 

How much does a hair drug test cost?

The cost of a hair drug test varies depending on the requirements of the instructing party.

To request a quote for hair drug testing, simply complete our online form, and a member of our Legal sales team will be in touch to discuss your needs.

You can also call 01 402 9466 or email testing@alphabiolabs.com for more information.

If you have received a quote for hair drug testing from another testing laboratory, we will match their price and reduce it by a further 5%: this makes AlphaBiolabs the most cost-effective solution for your legal drug testing needs.

 

How accurate is drug testing with hair?

Our hair drug testing is 100% accurate and reliable based on the samples we receive at our laboratory.

Here are just a few more reasons why you can trust the accuracy of AlphaBiolabs’ hair strand testing for court:

  • We have over 15 years’ experience providing first-class drug testing services for the legal sector
  • We have invested in the very latest drug testing technology for our state-of-the-art toxicology laboratory
  • We employ some of the foremost scientists in Europe
  • We follow cut-off guidelines for hair drug testing, as set by the Society of Hair Testing (SoHT)
  • Our laboratory is accredited to the quality technical standard of ISO 17025 (No. 2773) and certified to ISO 9001
  • All our legal sample collections are carried out by professional sample collectors, under chain of custody conditions
 

How long do drugs stay in hair?

Depending on the length of hair available for testing, and when the drugs were consumed, it is possible for drugs to remain detectable in a cut hair sample for up to 12 months, as advised by the Society of Hair Testing (SoHT).

 

What will the results of a hair drug test show?

AlphaBiolabs offers two types of drug test report.

A Certificate of Analysis is included as standard for legally-instructed drug tests and details which substances were (and were not) detected within the sample from the panel of drugs/drug metabolites for which analysis was requested.

A Statement of Witness is a more in-depth report with full analytical results, interpretation, and conclusions, and is available for an additional fee.

While both documents are invaluable for court proceedings, a Statement of Witness provides the most comprehensive interpretation of the findings, including disclosures provided at the time of sample collection (e.g. any hair treatments or prescribed medications) and the professional and objective expert opinion of the Reporting Scientist.

A drug test report will show whether one or more drugs were detected in an individual’s sample during a set period, depending on which testing method has been used (up to 12 months for head hair and body hair), with the amount of each substance considered either above or below cut-off levels.

However, head hair analysis is the only testing method that gives us the potential to determine a pattern of drug use over time, using segmented analysis to identify trends such as an increase or decrease in usage, depending on the length of hair selected (1cm of head hair = one month of growth).

AlphaBiolabs follows the Society of Hair Testing guidelines for cut-off levels (where applicable) for hair sample types.

 

What can affect the results of a hair strand test?

Certain hair treatments including bleaching, dyeing, perming, and straightening have the potential to impact the results of a hair drug test.

For this reason, reputable testing laboratories like AlphaBiolabs will always ask for full disclosure of any recent hair treatments so that this can be taken into consideration when preparing the results.

 

What factors are considered when compiling a hair drug test report?

The results of a hair drug test should never be interpreted in isolation. Several factors can influence how drugs are incorporated into the hair, meaning expert analysis is essential to ensure a fair and accurate assessment.

Factors that AlphaBiolabs’ Reporting Scientists will always consider when reporting hair drug test results, include: 

  • Hair type and colour – melanin levels in hair can impact drug incorporation, meaning darker hair may sometimes retain higher concentrations of certain substances.
  • Cosmetic treatments – chemical treatments such as excessive bleaching, dyeing, perming or straightening have the potential to affect drug retention in hair strands.
  • External contamination – environmental exposure to drugs (e.g. through smoke or physical contact) does not necessarily indicate use. Our reports consider the presence of metabolites – byproducts produced by the body after drug use – to help distinguish between active consumption and contamination. We also ensure the hair being tested is thoroughly washed first to ensure any surface contaminants are removed/minimised.
  • Biochemical properties of drugs – different drugs bind to hair at different rates, meaning some substances are more likely to be retained than others.
  • Variable growth rates of hair – Hair typically grows at an average rate of approximately 1 cm per month, as referenced by the Society of Hair Testing (SoHT). However, this rate can vary between individuals due to factors such as age, genetics, medical conditions, and ethnicity, potentially affecting the approximate time period represented by each hair segment.

Why are cut-off levels important for hair drug testing?

Cut-off levels play a crucial role in ensuring the accuracy and fairness of hair drug testing. Without cut-off levels, even trace amounts of substances could be reported, potentially resulting from passive exposure to drugs rather than active drug use.

One example of such a scenario is the ‘cocaine kiss’.

Cocaine can dissolve in saliva and be absorbed through the soft tissues in the mouth. This means that even a small amount of cocaine has the potential to be transferred to a non-cocaine user, through kissing.

Due to the sensitivity of modern-day drug testing, this can result in the person testing positive for cocaine even if they did not actively use the drug themselves.

At AlphaBiolabs, we follow internationally-recognised cut-off guidelines set by the Society of Hair Testing (SoHT), which bases its recommendations on extensive research across a diverse range of populations.

These scientifically established thresholds are:

  • based on data from thousands of cases, covering a wide range of sample donors.
  • reviewed regularly to reflect advancements in drug testing technology
  • designed to distinguish between actual drug use and incidental environmental exposure, preventing misleading conclusions

Our reports are not just data-driven but include expert analysis to help clients understand the significance of the results. Where results are close to the cut-off level, we provide additional insights to prevent misinterpretation.

What’s included in an AlphaBiolabs hair drug test report?

We are committed to delivering scientifically robust and transparent drug test results.

Our reports provide context and expert interpretation, ensuring that results are not taken at face value but considered holistically.

Our hair drug test reports include:

  • Sample donor information – including photo ID, and details of any disclosures made at the time of the sample collection (e.g. prescribed medications, drug/alcohol usage, environmental exposure to illicit drugs/close body contact with a drug user).
  • Substances found and detected levels – which drugs have been detected, along with their concentration levels, measured in nanograms per milligram (ng/mg) or picograms per milligram (pg/mg) of hair (analyte dependent).

  • Comparison with internationally-recognised cut-off levels – to ensure accuracy, the levels of substances detected are compared against scientifically validated thresholds. These cut-off levels play a fundamental role in helping to distinguish between actual drug use and potential external contamination.

    AlphaBiolabs also has analytical cut-offs for each analyte that are higher than the SoHT cut-offs to take into account analytical variation. Therefore, when a positive result is reported, there is no doubt that the compound is present within that tested sample. 

  • Interpretation of the test results, including relevant caveats and considerations – a drug test report should not simply tell you whether the sample donor has tested positive or negative for a certain substance.

    Our reports include expert analysis, considering factors such as possible external exposure to illicit substances, sample donor declarations, the presence of metabolites (which indicate active drug use), pattern assessments of active and previous drug use, and consideration of the natural variations in hair drug incorporation and rates of hair growth.

  • Segmented analysis – if requested, hair samples can be segmented to provide an insight into a pattern of drug use over time, rather than a single result for the entire period (overview analysis).
  • Contextual considerations – factors such as hair treatments, hair colour, sample donor declarations (such as prescribed medications/declared substance use), and the donor’s ethnicity are all carefully considered, to ensure a fair and accurate interpretation.

Can a person cheat a hair drug test?

For drug test results to be admissible in court, samples must be collected under strict chain of custody conditions, reducing the likelihood of tampering, and ensuring samples are collected from the right people.

Yet there are still some individuals who will attempt to ‘cheat’ a hair follicle test; something which can be easily prevented by using a trained sample collector.

Common methods include:

  • Wearing a wig
  • Attempting to provide a pre-cut hair sample that is not theirs
  • Having someone else attend the sample collection appointment on their behalf
  • Shaving off all head and body hair

While these methods are ineffective, it is important to note that excessive bleaching, dyeing, perming, or straightening of the hair has the potential to impact a drug test result.

For this reason, we will always ask for full disclosure of any recent hair treatments so that this can be taken into consideration when preparing the results.

 

What is the difference between a hair drug test, a nail drug test, and a urine drug test?

The main difference between a hair drug test, a nail drug test, and a urine drug test is the sample type used for testing.

However, each testing method also offers a different window of detection for drug use.

Hair drug tests and nail drug tests offer what is known as a ‘wide window’ of detection for drug use, with head hair and body hair providing a detection window of up to 12 months, and nail drug tests (using nail clippings) also providing a detection window of up to 12 months (six months for fingernails and 12 months for toenails).

A urine drug test provides a ‘narrow window’, with drugs only remaining detectable in a sample for approximately four days after they were consumed.

However, this period can vary depending on the drug type and quantities that have been taken.

 

Where can I get a hair test for drugs?

Understanding which drug testing methods will best suit your client, along with the ways in which people try to cheat the test, will help you secure a satisfactory outcome for your case.

At AlphaBiolabs, we have over 15 years’ experience providing first-class drug testing services for the legal sector, including hair follicle testing.

We also offer free sample collection for legally-instructed hair drug tests from our Dublin walk-in centre.

For expert advice on hair drug testing, or to request a quote, call AlphaBiolabs’ Legal team on 01 402 9466 or email testing@alphabiolabs.com.

 

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Marie Law AlphaBiolabs

Marie Law

Director of Toxicology at AlphaBiolabs
A highly-skilled and respected scientist with over 13 years’ experience in the field of forensics, Marie joined AlphaBiolabs in 2022 and oversees the company’s growing toxicology team. As Director of Toxicology, Marie’s day-to-day responsibilities include maintaining the highest quality testing standards for toxicology and further enhancing AlphaBiolabs’ drug and alcohol testing services for members of the public, the legal sector, and the workplace sector.

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