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.
To register a hair drug testing case, please contact our business partners, Lextox. They 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. Results will be despatched within 5 working days of receiving the sample.
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 recommended to wait two weeks following the suspected use of or exposure to a drug before collection of a sample so that the period of use/exposure is included in the collected sample.
We have a nationwide team of fully trained sample collectors who are skilled at taking discrete samples and will ensure that the integrity and chain of custody of the sample is maintained.
Each section of hair taken must contain at least 10mg of hair which is roughly the diameter of a standard drinking straw, depending on the hair type. Because accurate testing requires samples to be taken as close to the scalp as possible, our trained collectors ensure they gather enough hair while minimising any visible impact. They use scissors to cut the sample and, where possible, take it from the crown so the remaining hair naturally covers the collection site.
Head hair grows at an average rate of approximately one centimetre (cm) per month. The length of hair available at the time of collection will determine what time period can be analysed. For example, if a 3-month analysis is requested, we will require 3cm of hair.
Our business partners, Lextox, follow 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. A Lextox expert witness report provides a clear summary and interpretation of the results, including relevant cut‑off levels, and documents any declarations made by the donor before testing, such as the use of hair treatments or medications.
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.
If scalp hair is unavailable, body or facial hair can be used instead. Body hair has a different pattern of growth and resting (telogen) phases to head hair. Because of this, body hair samples cannot be segmented for month‑by‑month analysis, so the entire sample is analysed as a whole.
Our business partners, Lextox, analyse for chronic alcohol consumption by testing for breakdown products of alcohol which are incorporated into hair, specifically EtG and EtPa.
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.
Our hair strand alcohol testing measures two key biomarkers, ethyl palmitate (EtPa) and ethyl glucuronide (EtG), as standard. These markers are produced by the body when alcohol is consumed, allowing us to assess patterns of chronic, excessive alcohol use.
We have a nationwide team of fully trained sample collectors who will ensure that the integrity and chain of custody of the sample is maintained. Blood and urine samples can be taken at the same time as a hair sample.
Links to Cellmark’s standard Terms and Conditions can be found here as well as in our website footer. From the 2nd February 2026, Cellmark will be transferring its drug and alcohol testing service to our business partners, Lextox. Lextox’s Terms and Conditions, including their Service level agreement, can be found here.
From the 2nd February 2026, Cellmark will be transferring its drug and alcohol testing service to our business partners, Lextox. Lextox is a UKAS accredited testing laboratory No. 7516. For details UKAS accreditation please visit here.
Cellmark remains a UKAS accredited testing laboratory (Lab No. 2045) for relationship DNA testing.
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.