The ways people try to cheat drug tests

For as long as there have been drug testing services, people have been trying to find ways to cheat drug tests.

Of course, the only way to be certain of receiving a negative drug test result is to abstain from taking drugs in the first place. However, this does not deter people from trying to ‘fool’ the tests.

In this article, we discuss the ways that people try to cheat drug tests – and why these methods won’t work. 

How can drugs be detected by a drug test?

When a person uses drugs, a proportion of the drug and its metabolites are released into the bloodstream, with a small amount being excreted by the body in different ways.

This makes it possible to analyse a variety of samples for the presence of drugs including urine, saliva (oral fluid), hair and nails, with each drug testing method offering a different insight into a person’s drug use.

Oral fluid drug tests can detect drugs for up to 48 hours after consumption, while urine drug tests can detect drugs and their metabolites up to four days after drugs were consumed.

The rate at which head hair grows means that head hair drug tests provide a wide window of detection for drug use, making it possible to detect metabolites in the hair for up to 12 months after drug use, depending on the length of the hair.

Similarly, nail drug testing can provide an overview of up to 12 months for drug use (six months for fingernails and 12 months for toenails).

What are the ways people try to cheat drug tests?

Even though advances in toxicology and laboratory testing make it virtually impossible to ‘cheat’ a drug test, many people still attempt it when faced with the prospect of receiving a positive drug test result.

Here are some of the most common ways that people try to cheat drug tests.

Adding substances to a urine sample

There are people who believe that adding certain chemicals to a urine sample will prevent any drug use from being detected.

However, toxicology processes for urine drug testing are incredibly sophisticated, with reputable laboratories routinely testing for chemicals that are used to try and cheat the test.

If any of these chemicals are detected, this will be reported as a failed drug test, and another urine sample will be needed.

Drinking lots of water

It is a common misconception that drinking a lot of water before a urine drug test will help you pass the test.

However, because urine drug tests are extremely sensitive, it is unlikely that you would ever be able to cheat a drug test simply by drinking a large amount of fluid.

Drinking water or any other concoction before a test would only dilute a urine sample, but you would need to have had a significant quantity of fluids for this to happen.

Drinking too much water can also be dangerous, as you are diluting electrolytes in the body. This is referred to as ‘water intoxication’ which in extreme cases can be fatal.

In any case, laboratory analysis would always be able to tell whether a urine sample has been diluted.

Using synthetic urine or someone else’s ‘clean’ urine sample

Some people will try to use synthetic urine to pass a drug test: a method which simply will not work, as reputable testing laboratories are able to differentiate between synthetic urine and the real thing.

It is also quite common for people to try and pass off someone else’s ‘clean’ (drug free) urine sample as their own.

However, the temperature of the urine sample is always checked within a few minutes of sample collection, meaning that you are unlikely to pass a drug test by tampering with a urine sample in this way.

Dyeing or bleaching hair

Although some hair treatments have been known to lessen the concentration of drugs found in hair, it is extremely unlikely that you would be able to pass a drugs test simply by dyeing or bleaching your hair.

This is due to the way in which drugs find their way into the hair once consumed.

When a person takes drugs, they are broken down by the liver, and a proportion of the parent drug and its metabolites are absorbed into the bloodstream.

These drugs then enter the hair follicle and become trapped in the medulla, the innermost layer of the hair shaft. These substances remain trapped in the hair as it grows, meaning dyeing or bleaching would not remove drugs from the hair entirely.

Furthermore, during a legal drug test (when hair drug testing is most commonly used) a trained sample collector – such as those in AlphaBiolabs’ sample collection network and at our Dublin walk-in centre – will collect the hair samples under strict chain of custody procedures to ensure samples are collected from the right people and have not been tampered with.

As part of this process, the sample collector will always ask for full disclosure or any recent hair treatments, so that this can be taken into consideration when preparing the results.

Whatever the circumstances, a reputable testing laboratory will know how to spot the signs of any attempt to tamper with the hair ahead of a drug test.

Can you cheat a drug test?

Thanks to advances in modern toxicology processes, and continued innovation from testing laboratories like AlphaBiolabs, it is extremely unlikely that you would be able to cheat a drug test under any circumstances.

We have over 15 years’ experience providing industry-leading drug testing services for members of the public, the legal sector and the workplace sector.

Our toxicology laboratory is accredited to the international quality standard ISO 17025 and certified to ISO 9001. We employ top scientists and can test a variety of samples for the presence of drugs and their metabolites, including head hair, body hair, nails, urine and oral fluid (saliva).

If you have concerns about a loved one misusing drugs or simply want a drug test for other personal reasons, our easy-to-use Home Drug Test Kit can help you find the answers you need.

If you are a member of the public who requires a drug test for official matters (e.g. for work, child custody disputes or other legal matters), you will need a legal drug test.

Still have questions about which drug test is best for you? Contact our friendly and knowledgeable Customer Services team on 01 402 9466 or email

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Marie Law AlphaBiolabs

Marie Law

Head of Toxicology at AlphaBiolabs

A highly-skilled and respected scientist with over 13 years’ experience in the field of forensics, Marie joined AlphaBiolabs in 2022 and oversees the company’s growing toxicology team.

As Head of Toxicology, Marie’s day-to-day responsibilities include maintaining the highest quality testing standards for toxicology and further enhancing AlphaBiolabs’ drug and alcohol testing services for members of the public, the legal sector, and the workplace sector.

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