Can you test hair for drugs? How accurate is hair testing? Will the results stand up in court? We answer these questions in our latest expert guide…

Can you test hair for drugs?

Testing hair for drug usage is entirely possible and regularly undertaken on behalf of family courts, solicitors and social workers managing complex family cases.

At a specialist laboratory such as AlphaBiolabs, drug use from as far back as 12 months can be detected in head hair samples where there is sufficient length, and month-by-month analysis can be carried out to give a more detailed picture of a person’s drug habits within that 12 month period, or less where the hair is shorter.

Whilst it’s not possible to determine exactly how a person ingested a drug substance, it is possible to give a conclusive answer about whether or not that person has taken drugs.

So how are drugs incorporated into hair?

When a person ingests a drug, the substance reaches the liver where it is broken down and metabolised. Metabolites from that process then enter the blood stream which feeds every hair follicle in the body, causing those metabolites (or drug by products) to be tightly bound within the hair shaft and to remain so as the hair grows.   

Because of the rate at which head hair grows – typically 1cm a month – head hair samples can be used to determine a person’s drug usage as recent as 2 weeks ago.

How? When the drug by product arrives at the hair follicle it takes approximately 7-10 to reach the surface of the scalp. At around 14 days, the hair will have grown enough for the drugs to be incorporated into a cut hair sample. This means the hair closest to the scalp will reveal the most recent drug use – as recent as a fortnight ago.

Depending on the depth of analysis required, head hair samples can be cut into either 1cm sections to give a month by month analysis, or it can be cut into 3cm sections to give a 3-month overview.  

Body hair and drugs

Body hair can also be used to determine a person’s drug use, however, because of its inconsistent growth rate, it can only be used to determine an average concentration of consumption over 12 months. Body hair generally only has a life span of one year too, so up to a year’s usage will be stored within that hair.  

Drug testing without head or body hair

Where a person has little or no body hair, there is a third method of drug testing involving nail analysis. Whilst, like body hair, nail testing can only give a 12-month overview of usage, it can be useful in the absence of head or little body hair.

AlphaBiolabs has been carrying out drug and alcohol testing for the legal community, workplaces and the public since 2004.

Get a quote for hair drug testing here or visit our website for more information. Call us, on: 0140 29466 or email us, at:

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AlphaBiolabs is an accredited laboratory offering a range of drug testing services.