Will hot tub use affect my client’s hair drug test result?…and other questions

Lolita Tsanaclis

Lolita Tsanaclis

on Jul 8, 2022

In an article first published in The Review earlier this year, Cansford Laboratories founder Lolita Tsanaclis answers some of the most frequently asked questions around hair drug and alcohol testing.

If you are dealing with family cases involving child custody, you may at some stage require drug or alcohol testing to identify immediate use, demonstrate habitual use, or show that a client has stopped using drugs or alcohol over a given time period.

A drug test with hair is one of the most accurate forms of testing, and almost impossible to cheat - though people may try. It can provide confirmation of drug or alcohol use from seven days after use and show substance consumption over many months if the hair is long enough.

Having founded and run laboratories that provide hair testing services for 30 years, I have come across many different scenarios and have been asked many questions about factors that can have an impact on a hair drug test result. You may find clients asking you some of those same questions, hence the reason for sharing them - with answers - here.

What substances can be tested for in hair?

Any substance that gets into hair can be tested. Hair testing can reliably detect the use of alcohol and virtually all drugs – provided the drug has been tested for in the past. We have the methodologies for testing 157 different compounds, but there are some substances that are more commonly used than others.

We have a Common Drug Panel covering the nine most widely used drugs and drug groups, which was updated in January this year to include Ketamine, after noticing an increase in positive detection and requests for Ketamine testing. The panel now includes Amphetamine, Benzodiazepines, Cannabinoids, Cocaine Group, Methadone, Opiates Group, Methamphetamine Group, Tramadol and Ketamine.

 What is the difference between testing head hair and body hair?

In terms of the accuracy of results, there is no difference. Body hair is just as accurate as head hair as a marker of drug or alcohol use; and both are collected and analysed in the same way. However, when it comes to the timeframes covered by each test type, there are some differences.

While both head and body hair grow at a reasonably constant rate of 1cm per month (within a range of 0.7 to 1.5 cm), the approximate timescale covered by a head hair test is more representative of substance use when compared to an equivalent length of body hair.

This is because hair exists in one of two phases: resting or growing. In the resting phase, hair does not grow but still contains traces of substances from previous use. Estimates show that 40-60% of body hair remains in the resting phase, compared with 10-15% of head hair. This means that a 3cm sample of body hair would represent a period two to three times longer than a head hair sample of the same length, despite similar growth rates.

For this reason, if a drug test with hair is ordered to cover a specific time period, and both head and body hair are available, we would always recommend using head hair. And if sectional analysis is required to demonstrate that your client has changed their drug use - to prove to a court that they are fit to retain or regain custody of a child, for example - head hair should be used, because sectional analysis of body hair is not possible.

Why can’t people provide their own hair sample?

There are several reasons why it is better to have a sample taken by a professional, trained collector. The first is chain of custody, which exists to guarantee the integrity of the sample taken, ensuring the sample - and therefore the results - are linked to the correct donor.

This starts with the collection. Professional collectors are trained to follow a finely honed procedure that includes checking donor identification and a completing a declaration that the sample has been collected in accordance with the specified collection process, before sending the sample back to the lab.

Don't undermine your case

One way of explaining this to your clients is that if there could be any doubt in the mind of a judge that the hair sample tested belongs to the donor, it could undermine the entire case. Knowing that a specialist collector took the hair sample, and that the test and results have been processed by an accredited laboratory, gives you a solid chain of custody.

Quality is everything

The second is the quality of the hair sample. Clients will sometimes ask if their sister/brother/friend/mum can take the sample, because they’re a hairdresser, but the fact is that the way a sample is taken can have an impact on the test results. To accurately segment the hair so that it shows substance use (or otherwise) across a specified time period, a straight cut is required when the sample is taken. If your client is concerned about the test leaving a bald patch, you can reassure them that the sample collection site will not be visible.

In addition, professional collectors are trained to take samples that will give the most accurate test results. If your client has stopped using drugs or alcohol, naturally they will be keen for the test to show this. If the hair sample is taken by someone who is not trained, they may take a sample from the end of the hair – i.e., a distance from the scalp. Bearing in mind that hair testing can detect substance use over several months, it is the hair growth closest to the scalp that shows the most recent substance use – or lack of it. A sample of hair in the resting phase may show up past drug use and could impact on the outcome for your client.

Can bald people be hair tested?

If a hair test is ordered to cover a specific time period and head hair is not available - for example, if the donor is bald, or if they have bleached their hair so significantly that it may impact on test results - then body hair should be used.

There may also be instances where body hair is not available, either: if the donor has alopecia, for example, or can’t have their hair cut for religious reasons. In these situations, fingernail testing for drugs can be used instead, and it is commonly used in situations where hair testing is the preferred method, but hair sample collection is challenging.

When this is the case, and body hair or a nail drug test is used instead of a hair sample, it is important to understand how the detection timeframe for the sample could be affected - as mentioned in the earlier question about head hair vs body hair – because this can make a crucial difference to the test result, and potentially to your case.

In these situations, the collector would note the reasons why head hair cannot be used, the test report would factor this in to the findings and, if you need further information or clarification, your lab should be happy to talk you through the results and their implications.

Do pregnancy hormones or menopause affect test results?

Hormones can affect hair growth rates. As such, this could have an impact on the time period shown in test results, but it would not affect the accuracy of the result.

 Would using a hot tub affect a hair test result?

There is no scientific research that I know of into hot tub use and hair testing. What is most likely to affect a test result is chemicals getting into the hair but, even then, a person would need to have their hair under water for a long time for the result to be significantly affected.

Swimming for prolonged periods on a regular basis in a chlorinated pool is more likely to affect a hair sample than the water or steam from hot tub use but, even then, prolonged exposure to chlorine in a swimming pool would not remove the trace of drug and the test would still show as positive for people using drugs regularly.

 Does hair colour have an impact on a drug test result?

It can. People with naturally dark hair will carry more evidence of drug in their hair than people with naturally lighter hair, even with the same level of drug use. The more melanin there is in the hair, the more the drug will be bound into it. This is something that would be observed at the collection stage and recorded by the person writing up the test report, who will have experience of this and will factor it into their report.

How quickly will I get my test results?

Last but by no means least: this is the question we are asked most frequently, and I imagine you will be, too. The answer is that timescales vary from lab to lab. Some providers outsource testing, while others complete it in house, and this often has an impact on timeframes. All our testing is done in house at our laboratory in Cardiff, and we turn around results in 24 to 48 hours, which we specify on test documentation to enable you to reassure your clients.

This is by no means an exhaustive list of questions we are asked around drug and alcohol testing, but they are among the most asked. If you come across other questions in your work with clients or when commissioning drug or alcohol tests, do get in touch ( and we will be happy to help answer them.

Video Credit: Video by INESby from Pixabay 


Lolita Tsanaclis

Lolita Tsanaclis

Dr. Lolita Tsanaclis, Chief Scientific Officer of Cansford Laboratories Limited, has been developing methods for the analysis of drugs in hair since 1993. She has been involved in drug testing using hair, blood and oral fluid samples for medico-legal and workplace sectors for over three decades. Dr Tsanaclis is published extensively as author and as co-author in highly regarded peer-reviewed publications and scientific presentations.

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