Overview vs. Segmented Hair Analysis

As head hair grows at an average rate of 1 cm each month.
Drug use can be established over a defined period depending on the length of hair selected.

What drugs can be detected?

The standard drugs we test for in head hair are:

We can also arrange hair drug testing for GHB, LSD, Spice, Steroids, Tramadol and other less common drugs for an additional fee.

Types of analysis

An overview analysis is beneficial to obtain a general indication of drug use. This could range from 3 cm to identify drug use within that 3-month time period, up to 6 (2 x 3) or even 12 (4 x 3) months, dependent on the length of hair available.

A 6-month overview could also be used to provide two results: one for the earlier 3 months and a second result for the later 3 months. If a more detailed analysis is needed, segmented would be the preferred option.

By segmenting head hair samples into monthly 1 cm sections, a month-by-month profile of drug use can be attained to provide a detailed historical profile of an individual’s drug exposure.

how is a hair sample taken

If a hair drug test was to cover 6 months, a month-by-month analysis will provide six individual results for each of the months. As such, segmented analysis is especially useful if you need to obtain a trend in drug use, such as to see a decrease or increase in drug use over time, or to highlight intermittent use.

In an overview test, any episodes of drug taking are averaged out over the period being tested. For example, if an individual has not taken drugs for 2 months but then takes an excessive amount in the next month, drug markers will be found along the entire length of the hair. In the case of segmentation, the episode of drug taking can be pinpointed to the actual month.

Which test should you choose?

Answering the questions of When and How often your client used a substance can make or break a family law case. It is therefore essential to choose a test method that is right for your case.

If a 3-month overview drugs of abuse test is selected, even if an individual uses drugs occasionally, the test may come back positive for the whole 3-month period. This result implies that the sample donor had been abusing drugs during the whole period analysed.

To overcome this, segmented hair drug testing could be performed over the same 3-month period. The sample donor could show positive one month and negative the other 2 months. This would provide a more accurate assessment of the individual’s drug abuse/abstinence when presented to the court for scrutiny.

Cases such as this demonstrate the importance of an expert advising on the appropriate test to use. Taking an average of drug levels in a specified hair section without the knowledge of levels in the hair section prior to the period of interest can produce misleading results.

Examples of the head hair analyses regularly performed

Analysis type required Number of segments Reported time period Type of Test
3 months 1 3 months Overview
3 months 3 3 individual months Segmented
6 months 2 2 x 3-month periods Overview
6 months 6 6 individual months Segmented

If you have further questions about overview vs. segmented hair analysis

For expert advice on hair testing and other drug testing solutions, please call our Customer Services team on 01 402 9466 or email us at

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Gail Evans AlphaBiolabs

Gail Evans

Technical Trainer at AlphaBiolabs

A professionally-trained forensic scientist, Gail joined AlphaBiolabs in 2012 and holds the role of Technical Trainer.

Her day-to-day responsibilities include delivering in-depth training sessions both internally and externally, covering DNA, drug, and alcohol testing.

Throughout her career at AlphaBiolabs, Gail has held a variety of roles, including within the Legal and Workplace sectors of the business.

Before joining the company, Gail was a practicing forensic scientist with 25 years’ experience working for the Forensic Science Service, attending scenes of crime, and analysing physical and biological material with potential evidential value.

Gail also holds qualifications in chemistry and is a Lead Auditor for the ISO 9001 standard, the international standard for quality management.

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