Hair Drug Testing FAQs

AlphaBiolabs offers hair drug testing services for private legal or official matters, for the legal profession, including family law solicitors, social workers, and local authorities, and for the workplace.

This article answers some of the most frequently asked questions relating to hair drug testing.

How does head hair grow?

Normal head/scalp hair growth occurs in a cycle consisting of four phases. After continuous growth in the anagen (growing) phase which may last for several years, cell division stops, and the hair bulb begins to degenerate within about 2 weeks (catagen phase).

The hair then stops growing but remains in the skin for 2-6 months (telogen phase) until a new hair is formed and pushes the old one out (exogen).

It is estimated that 10-15% of all hairs are in the telogen phase at any given time with the length of time increasing with age and dependent on the hair type.

Scalp hair from the posterior vertex is the preferred sample for time-resolved testing as it has the most consistent growth rate, with the highest percentage of follicles actively growing (anagen phase).

Hair typically grows at an average rate of approximately 1cm 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

It takes around two weeks for newly formed hair containing the drug to be available for inclusion within a cut hair sample.

How does body hair grow?

Body hair has much more variable growth and resting cycles than scalp hair.

With body hair, 40–60% of the hair remains in the resting phase, making it unsuitable for segmented analysis. This means that deriving an accurate time frame of drug use from body hair is not possible.

It can be assumed that any drug use occurs within the total life cycle of the body hair; however, it is not possible to tell more precisely when the sample donor has consumed these drugs.

If a substance is detected using a drug test, this may represent very recent or older drug use/exposure. It may also represent drug use/exposure throughout the entire period of growth.

Consequently, it is not possible to determine if the pattern of drug use disclosed by the sample donor is consistent with the analytical findings.

How are drugs incorporated into hair?

After entering the body, drugs are transported by the blood stream, reaching all organs and tissues. Drugs are eliminated in both sweat and sebum; both secretions bathe the hair shaft as it grows, contributing to the drugs incorporated into hair.

Consequently, drugs are incorporated into the hair:

• directly from the blood supply and
• from sebum and sweat bathing the hair

In contrast to blood, parent drugs are more commonly detected in hair. For example, 6-monoacetylmorphine (6-MAM) – the primary compound of heroin – and cocaine are generally found in higher concentrations in hair than the respective metabolites, morphine and benzoylecgonine.

Basic drugs, such as amphetamines and cocaine, incorporate into hair to a greater extent than neutral or acidic drugs and are present in higher concentrations in hair compared with benzodiazepines and cannabinoids.

Cocaine metabolites (benzoylecgonine, norcocaine and cocaethylene) have a lower cut-off (0.05 ng/mg) when compared to the parent compound cocaine (0.5 ng/mg). Therefore, it is not uncommon for cocaine metabolites to be above the cut-off, but for the parent compound cocaine to be below the cut-off and reported as ‘negative’.

Despite being known metabolites of 6-MAM and cocaine respectively, morphine and benzoylecgonine may also be produced outside the body by chemical hydrolysis under strong acidic or alkaline pH.

Unlike some other hair testing laboratories, AlphaBiolabs runs cocaine/benzoylecgonine and 6-MAM/morphine hydrolysis tests on every run, ensuring that any benzoylecgonine or morphine detected originated from the sample, and are not a result of chemical hydrolysis.

We have strict criteria within the toxicology laboratory, and we will not report anything that does not pass.

Consequently, if the internal hydrolysis fails for cocaine/benzoylecgonine or 6-MAM/morphine and they are the only cocaine or opiate compounds detected, AlphaBiolabs does not report the results, and the sample will be repeated. However, if there is no hair remaining, a further sample will be required, and a recollection organised.

What are the different levels for hair drug testing?

The low, medium, or high range provided is derived from statistical analysis of positive samples analysed at AlphaBiolabs:

• Low – lies below the 25^th percentile^*
• Medium – lies between the 25^th and 75^th percentile^*
• High – lies above the 75^th percentile^*

^*Of dynamically updated positive cases

However, the level does not refer to the amount of drug consumed and is provided for guidance only.

The test results provided by AlphaBiolabs are obtained using High Performance Liquid Chromatography tandem Mass Spectrometry (HPLC/MS/MS).

This is a highly sensitive and specific analytical technique which means that analyte identification is unequivocal, and it can only be that compound.

However, due to the sensitivity of the analysis, occasionally only a qualitative result can be reported i.e. detailed as ‘detected’ rather than a numerical value. This does not affect the overall interpretation of the findings.

In such cases, we will be unable to provide a level for that analyte but will provide a level for any associated compounds such as heroin and cocaine and their respective metabolites, morphine or benzoylecgonine.

How accurate is a hair drug test?

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

We are accredited to the quality technical standard of ISO 17025 and certified to ISO 9001.

We follow cut-off guidelines for hair drug testing as set by the Society of Hair Testing.

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.

When testing hair, how can external exposure to drugs be ruled out?

External contamination has been extensively investigated by researchers, with the greatest challenge in attempting to recreate realistic contamination scenarios.

Consideration is given to the condition of the hair sample, which may be damaged through natural wear and tear or chemical treatment, and to the porosity of the hair. All these factors will affect the incorporation of drugs from external contamination and, conversely, the loss of drugs from the hair following use.

Passive exposure to a drug through smoke and/or direct contamination (i.e. the drug being in direct contact with the hair, such as through contaminated hands) may result in the presence of detectable levels.

Therefore, the method used by AlphaBiolabs for the analyses of drugs in hair samples involves the decontamination of the hair samples through a series of three chemical washes, which are kept by AlphaBiolabs for further analyses if requested.

Although these washes may not, on occasion, remove 100% of a drug (particularly after heavy contamination of the surface of the hair), the monitoring of the washes may allow the discrimination between the active direct use of a drug and environmental exposure.

How does hair dye affect my client’s test results?

It is well documented that chemical hair treatments such as bleach and dye can damage the hair shafts and have the potential to reduce the levels of any drugs, metabolites and alcohol biomarkers present in hair, possibly to a level below the cut-off.

However, it is not possible to specifically determine to what extent the treatment may affect the results obtained in a specific case.

Consequently, although increasing concentrations towards the scalp could indicate an increase in drug use, when treatments have been used, it is not possible to rule out that the concentrations in the oldest hair segments have been decreased due to the chemical treatment exacerbated by the washout effect.

Is it possible for a client to get a residual positive result on a drug test, after a period of abstinence?

One of the major advantages of hair testing is that it provides a retrospective time frame of an individual’s drug use or period of abstinence.

Normal scalp hair consists of approximately 85% of actively growing hair (anagen phase) and approximately 10-15% of hair not actively growing (catagen and/or telogen phase).

The catagen/telogen phase can last up to six months in some cases. Therefore, the hairs that were not actively growing prior to the collection could still contain residual drugs from earlier use.

Segmental hair analysis can address any changes in drug use. Studies have shown that the duration for which a drug is no longer detected in a hair sample after abstinence can also be influenced by the extent to which that drug was originally consumed, i.e. if an individual has not consumed a drug heavily prior to ceasing its consumption, then a drug hair result may be negative relatively quickly.

However, after heavy use, it may take up to six months to completely disappear from the hair segments closest to the root.

Therefore, if the date of abstaining from drug use was over six months prior to the sample collection, a positive residual drug result is unlikely, as the hair sample collected would not be expected to contain any of the resting phase hair during the active use.

It is only when negative results are obtained for a hair segment that the findings support drug use ceasing.

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.

How much does a hair drug test cost?

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

If you have received a quote for a hair drug test from another testing laboratory, we will match their price and reduce it by a further 10%. This makes AlphaBiolabs the most cost-effective solution for your legal drug testing needs.

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

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

How can I get a quote for a hair drug test?

It’s easy to request a quote for a hair drug test now.

Simply contact our New Enquiry team on 01 402 9466 / testing@alphabiolabs.com to discuss your case.

Alternatively, use our online quote form and a member of the team will be in contact to discuss your requirements.