Will one night of drinking show up in a hair follicle test?

Hair follicle tests typically analyze the hair shaft for drug metabolites using chromatography and mass spectrometry. Alcohol testing in hair is more complex and less common compared to drug testing. Alcohol can be detected in hair by looking for ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEEs), which are markers of alcohol consumption. However, one night of drinking is unlikely to result in detectable levels of these markers in the hair shaft. Hair analysis for alcohol typically reflects longer-term consumption patterns. For a positive result, there needs to be significant and repeated exposure, not just a single incident. Concentrations of these markers accumulate over time, making occasional or one-time drinking less likely to be detected.

Can a hair follicle test go back 12 months?

Time frame: Hair follicle tests can analyze drug use over an extended period of time. The general rule of thumb is that hair grows at a rate of about 1 cm per month. Therefore, a 12 cm length of hair can potentially reflect drug use over the past 12 months . Testing method: Hair samples are typically taken from close to the scalp, and the length of hair analyzed can determine the retrospective window. A 12-month time frame would require a sample approximately 12 cm in length. This month-by-month analysis allows for a detailed history of drug use. Testing works by segmenting the hair into monthly sections if needed, which provides a detailed view of drug use patterns over the specified period. For confirmation testing, methods like mass spectrometry and chromatography ensure accurate detection of drugs and metabolites. Drugs such as codeine, oxycodone, methadone, and barbiturates can be detected in hair, provided the concentration meets the cutoff levels for a positive result. Hair analysis can be a powerful tool for detecting long-term drug abuse due to its ability to reveal concentrations of drugs over an extended period of time.

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If you are applying for a new job or dealing with a legal case, there’s a chance you might need to take a hair follicle test. This type of test involves examining your hair to see whether or not you have a history of drug usage, so it’s no surprise that it can feel stressful or invasive to some. Many people worry that hair follicle tests can detect drug use that happened months ago or identify drugs not found in urine tests. Do you really need to worry about a hair follicle test? Explore our guide to see just how far back they can detect drugs.

Table of Contents

What Is Hair Follicle Testing?
- Substances Detected During Follicle Testing
The Science Behind Hair Growth and Follicle Tests
Disproving the 12-Month Myth
- Realistic Detection Windows for Hair Follicle Tests
Potential Limitations of Hair Follicle Testing
Final Thoughts
FAQ
- References

What Is Hair Follicle Testing?

Hair follicle testing is a type of test that can identify drug or medication usage. It works by collecting a few strands of head hair (body hair can also be collected if necessary) and looking for the presence of certain drug metabolites inside of your hair. These substances are chemicals that your body generates while breaking down drugs. The metabolites end up in your bloodstream and eventually travel to your scalp. The protein structure of your hair can trap these metabolites and keep them long after they’ve left the rest of your body.

Substances Detected During Follicle Testing

Some follicle tests may only check for a specific drug in your system while others may examine your hair more thoroughly for any trace of any type of drug.

Common substances found in hair sample test results include:

Alcohol
Cannabis (THC)
Heroin and other opioids (including opiates)
Cocaine
Amphetamines
Methamphetamines
MDMA
Phencyclidine (PCP)
Ketamine
Fentanyl
Benzodiazepines

The Science Behind Hair Growth and Follicle Tests

To understand how long a hair follicle test lasts, it’s important to consider how hair growth and drug metabolites work. On average, people grow around half an inch of hair every month. This means that you grow around six inches of new hair each year. However, there is a lot of variation in hair growth rates. The food you eat, your age, and your personal metabolism can all affect how fast or slow your hair grows.

The drug metabolites that a test looks for are usually bound to the protein or the melanin in your hair. They only show up in the hair you grow around seven to 10 days after drug usage. Therefore, hair from a couple of years ago isn’t going to have drug metabolites from the drugs you took a month ago, whether prescription drugs or others.

Once metabolites end up in your hair, a lot of lifestyle changes affect how long these metabolites last. Hair treatments like bleaching or perming can affect hair drug testing, and even the shampoos you use will affect how long drug metabolites last. The amount you sweat, how dark your hair is, and how oily your hair naturally is can all affect the amount of drug metabolites in your hair.

Disproving the 12-Month Myth

As you can see, a lot of different factors go into the detection window for a hair follicle drug test. Many people think these tests can detect substances up to 12 months in the past, but this is mostly a myth. This rumor tends to get spread because it’s a simple, round number that clearly shows the difference between hair and urine drug tests.

The reality is that hair follicle testing windows are a lot less precise. If two people take the same amount of a drug six months before a test, one person might test positive while the other tests negative. Everything from your diet to your personal hygiene habits will affect how accurate a hair follicle test is and how far back it can go. The amount of drugs you take and how often you take them also affects whether or not a detectable number of metabolites appear in your hair for months to come.

Realistic Detection Windows for Hair Follicle Tests

The length of time the test looks at will heavily depend on the length of hair collected for the test. In some cases, it might theoretically be possible to detect drug usage 12 months back or even further. However, most standard hair follicle tests only look at your recently grown hair. Especially if you have shorter hair, it’s impossible to see which drugs you were using a year ago. To help standardize testing, many labs only collect hair within 1.5 inches of the scalp. This means that they usually cannot detect drug usage more than 90 days in the past. The average hair follicle test is just for the past three months of your life.

Feature	Description
Detection Period	Can theoretically detect drug usage 12 months back or further, but standard tests typically focus on more recent periods.
Hair Length Collected	The length of hair collected heavily influences the detection period. Shorter hair limits historical detection.
Standard Practice	Many labs collect hair within 1.5 inches of the scalp to help standardize testing.
Detection Capability	Standard hair follicle tests usually cannot detect drug usage more than 90 days in the past, covering roughly the past three months.

Potential Limitations of Hair Follicle Testing

In addition to having very vague detection windows, hair follicle tests are also falling out of favor because they aren’t always accurate. 2017 research suggests that false negatives are fairly common. If a person’s hair hasn’t trapped a lot of drug metabolites, it can be harder for a hair follicle test to detect them. A 2015 study found that only about half of the people who reported recent cannabis use tested positive for the drug in a hair follicle test. Accuracy rates can range from around 2.9% to 65% depending on the drug.

Another challenge of hair follicle testing is that it works best on long, untreated hair. However, in most cases, it can be very hard to dictate how people care for their hair. By the time a hair follicle test is ordered, a person may have cut their hair or treated it in a way that makes it harder to detect drug metabolites.

Final Thoughts

Ultimately, hair follicle tests can be a useful tool, but they’re not entirely foolproof. Until you take the test, it can be quite hard to tell whether or not a hair follicle test will detect past drug usage. If you’re tired of having to worry about how far back a hair follicle test can detect drugs, getting clean is one of the most effective solutions. Sober living makes it easy to face drug screenings with confidence.

At Live Free Recovery Services, we’re dedicated to helping our clients succeed. We offer compassionate, evidence-based care that gives you the tools you need to overcome addiction. To learn more about our services, contact our team today.

FAQ

Will one night of drinking show up in a hair follicle test?
Hair follicle tests typically analyze the hair shaft for drug metabolites using chromatography and mass spectrometry. Alcohol testing in hair is more complex and less common compared to drug testing. Alcohol can be detected in hair by looking for ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEEs), which are markers of alcohol consumption.

However, one night of drinking is unlikely to result in detectable levels of these markers in the hair shaft. Hair analysis for alcohol typically reflects longer-term consumption patterns. For a positive result, there needs to be significant and repeated exposure, not just a single incident. Concentrations of these markers accumulate over time, making occasional or one-time drinking less likely to be detected.
Can a hair follicle test go back 12 months?
Time frame: Hair follicle tests can analyze drug use over an extended period of time. The general rule of thumb is that hair grows at a rate of about 1 cm per month. Therefore, a 12 cm length of hair can potentially reflect drug use over the past 12 months.

Testing method: Hair samples are typically taken from close to the scalp, and the length of hair analyzed can determine the retrospective window. A 12-month time frame would require a sample approximately 12 cm in length. This month-by-month analysis allows for a detailed history of drug use.

Testing works by segmenting the hair into monthly sections if needed, which provides a detailed view of drug use patterns over the specified period. For confirmation testing, methods like mass spectrometry and chromatography ensure accurate detection of drugs and metabolites. Drugs such as codeine, oxycodone, methadone, and barbiturates can be detected in hair, provided the concentration meets the cutoff levels for a positive result.

Hair analysis can be a powerful tool for detecting long-term drug abuse due to its ability to reveal concentrations of drugs over an extended period of time.

References

https://www.emcdda.europa.eu/activities/hair-testing_en
https://www.medicalnewstoday.com/articles/325013
https://www.fastestlabs.com/blog/drug-alcohol-dna-testing/hair-drug-test-myths-facts/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4080811/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5324538/