Hair Drug and Alcohol Testing FAQs

Testing hair samples is a non-invasive method of providing evidence of an individual’s history of drug or alcohol use. It can provide a record over a longer period of time (months rather than days) than any other sample type such as blood, urine or oral fluid.

You can register your hair drug testing case using our online registration service or by calling Cellmark's dedicated Customer Services team on 0800 036 2522 We will then arrange a hair sampling appointment for you or your client with one of our professional mobile samplers at a location and time that is convenient. Testing on average takes 5-7 working days (after receipt of the sample) and the test report will be despatched by email or first class post.

Hair is fed by a blood supply so substances that are circulating in the bloodstream can become incorporated into the growing hair. Hair can also incorporate drugs and other substances from sweat or sebum (an oily substance secreted by the sebaceous glands that helps to prevent hair and skin from drying out) or from environmental exposure to smoke or vapour.

Every hair will go through three phases: growing, transitional and resting. The growing phase can last from 3 to 7 years. Transitional phase lasts about 2 to 4 weeks. The resting phase can last from 3 to 4 months. Resting is the natural process that replaces old hairs with new hairs. It is normal to lose about 50 to 80 hairs per day.

A hair sample will normally have a selection of hairs in each of the phases of growth and this is taken into account in our analysis.

It is estimated to take approximately 5-7 days from the time of drug use or exposure for head hair containing the drug markers to grow above the scalp and be available for cutting and analysis. It is recommended to wait at least three to four weeks following the suspected use of a drug before collection of a sample so that the period of use/exposure is included in the collected sample.

Cellmark uses a team of professional samplers who visit solicitors’ offices and courts to take samples (blood and urine samples for supplementary alcohol marker analysis can be taken at the same time). The samplers are skilled at taking discrete samples and will ensure that the integrity and chain of custody of the sample is maintained.

For an accurate test we require a sample which is the approximate diameter of a standard drinking straw. This amount of hair is unlikely to give any considerable cosmetic concern to the donor.

Head hair grows at an average rate of approximately one centimetre (cm) per month with a range of between approximately 0.7 and 1.5cm. At Cellmark we assume the population average of 1cm per month in the calculation of section dates and the length of hair available at the time of collection will determine what time period can be analysed.

Cellmark follows the guidance from the Society of Hair Testing (SoHT) regarding the recommended cut-off concentrations for drugs in hair samples, above which drugs should be reported as being detected. Details of the individual cut-off concentrations for each drug are provided in our Hair Drug Testing Critical Reporting Limits document which can be found here.

Testing a single section of head hair provides an overview for that period of time. A maximum of 3cm (i.e. one 3 month period)can be tested. Alternatively, head hair samples can be divided into individual 1cm lengths to provide an approximate “month by month” report to demonstrate patterns of drug use or abstinence. The number of sections that can be tested for the presence of drugs will be dependent upon the length of sample available.

Body hair has a similar rate of growth as head hair, with a range of between approximately 0.9 and 1.1cm per month, but it has a different pattern of growth and resting phases. It has been estimated that body hair has a much higher proportion, approximately 40% - 60%, in the resting phase compared to only 10% - 15% for head hair.

As a consequence body hair samples are not divided into sections for analysis and any use of or exposure to a detected drug may have been in the weeks prior to the sample collection or many months earlier than this.

Cellmark analyses for chronic alcohol consumption (defined as an average consumption of 60 grams of pure alcohol per day (7.5 units) over several months) by testing for breakdown products of alcohol which are incorporated into hair, specifically EtG and EtPa.

Higher levels of these markers indicate that more alcohol has been consumed. However, since the levels of these ‘direct’ markers of alcohol consumption can be influenced by a number of factors including cosmetic treatments and thermal hair straightening tools, it is recommended that the results should not be used in isolation but should be considered alongside other tests and factors in the case.

Ethyl glucuronide (EtG) is a product of alcohol degradation in the liver and is incorporated into hair via blood vessels supplying the hair follicle and also from sweat.

The fatty acid ethyl ester, ethyl palmitate (EtPa), is another marker used to indicate alcohol consumption. It is formed by enzymes in blood and tissues after alcohol consumption. EtPa is incorporated into the hair via the blood as well as from the oily sebum produced by the body’s sebaceous glands.

Cellmark uses published, validated cut-off levels for the detection of EtG and EtPa in hair which are internationally accepted and recommended by the Society of Hair Testing.

A result above these cut-off levels is strongly suggestive of chronic excessive alcohol use.  Below these levels the results are more consistent with normal social drinking and may be used to corroborate a claim of abstinence.  However, it is never possible to rule out one-off alcohol use or occasional binge drinking with hair testing alone.

EtG is considered the more reliable alcohol marker in hair, but the combination of EtG and EtPa tests is recommended. Please be aware that low levels of EtPa may be found in the hair of teetotallers and can therefore give a false positive if considered in isolation.

Cellmark concurs with the Society of Hair Testing consensus (revised in 2019) which recommends that testing for EtG and EtPa (together) should be used as part of an overall case assessment. Cellmark also offers blood as well as urine tests which look for other ‘indirect’ indicators of alcohol consumption.

A separate hair sample (minimum 3cm) will be required for alcohol analysis. We only offer an overview analysis (not month by month) to ensure the reliability of the interpretation and do not recommend body hair for the same reason.

Carbohydrate deficient transferrin (CDT): transferrin is a protein in blood which is affected by alcohol consumption. A period of excessive alcohol consumption leads to an increase in the level of CDT. Levels revert to normal after several weeks of abstinence so it only provides an indication of consumption in the two weeks prior to sampling.

Liver Function Testing (LFT) looks at markers within the blood to check how the liver is performing; gamma-GT (GGT), alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Excessive consumption of alcohol will affect liver function and produce raised levels of several these markers. Please note that various medical conditions and treatments can also affect liver function.

Ethyl Glucuronide (EtG) and Ethyl Sulfate (EtS) are both breakdown products produced by the body after the consumption of alcohol. Urine testing for EtG and EtS will detect alcohol use up to approximately 80 hours after drinking ie recent use. However on its own, urine testing is not indicative of chronic excessive consumption.

Our blood and urine testing services are provided in partnership with our partner laboratory.

Cellmark uses a specialist team of samplers who can visit your offices to complete this task (blood and urine samples can be taken at the same time as a hair sample).

Any hair not used during the analysis is stored at room temperature in the sample collection envelope for a minimum of two years. Urine samples are stored for 4 weeks and blood samples for six months.

At the end of the agreed storage period hair samples will either be destroyed as clinical waste or may be anonymised and used for validation testing and method development, unless instructed otherwise.

Cellmark's test reports are retained for a minimum period of 2 years. Customer data is stored by our sampling organisation for 13 months in its original form, it is then anonymised and moved to an archive database.

Links to Cellmark’s standard Terms and Conditions can be found here as well as in our website footer, where a number of our other policies and statements can be found including the Service Level Agreement for our Hair toxicology service (Hair Tox SLA) and also our Hair Drug Testing Critical Reporting Limits document which has technical information about the service.

Cellmark is a UKAS accredited testing laboratory No. 2045. Laboratory analysis will be carried out by Cellmark or Cellmark’s appointed ISO17025 accredited laboratory with all toxicology results assessed and reported by Cellmark’s experienced toxicologists. For details of UKAS accreditation please see our critical reporting limits information. 

Phosphatidylethanol (PEth) is a specific and reliable marker for the detection of recent  alcohol consumption.  When someone drinks, alcohol is absorbed into their blood where it reacts with a substance (phosphatidylcholine) found in the cell membrane of red blood cells to form PEth.  PEth accumulates on the surface of the person’s red blood cells as more alcohol is consumed, so the level of PEth provides an indication of whether alcohol use has been occasional, moderate or excessive in the previous 4 weeks.