Let’s get real for a second.
How likely is it that a hair test for drugs will come back positive?
The answer depends on a host of factors. Each strand of your hair is nourished by blood vessels that carry all sorts of substances – including traces of potential drugs you may have consumed.
A hair drug panel takes a deeper look into the past than other kinds of tests, so it’s important to understand how much of a drug is too much.
Keep reading to find out.
Substance Detection in a Hair Test for Drugs
Why go for the hair?
Drug metabolites – the end products of your body’s metabolism doing its thing – are distinct chemical signatures that remain after your body has finished processing a drug. Even minimal contact with a drug can cause it to bind to your hair follicles.
When a laboratory receives a hair sample, a technician will analyze it to detect what’s in it. They’ll wash the hair (to remove contaminants), cut it into segments, and perform a series of chemical tests.
The actual detection is two-tiered. The first is a broad drug panel using immunoassays to identify potential positive results. The second test confirms the results of the first, based on whatever came back positive.
What “Substance Detection” Really Means
“Substance detection” goes beyond “finding drugs in somebody’s hair”.
It’s about interpreting what those findings mean. Whether it’s within the context of the law, of employment, or of a social setting, it’s not just about the presence (or absence) of a drug.
The presence of a drug metabolite doesn’t indicate recent use. It simply means that, at some point in the past, a person has ingested a substance and that substance left a footprint behind.
The detection of a substance is influenced by a host of factors. Age and diet matter, as does the amount and frequency of drug use. Metabolism and hair growth affect the amount of a substance deposited in hair follicles.
Even hair color is a factor – darker tends to bind to more metabolites because it’s naturally higher in melanin.
How Hair Drug Testing Works
Hair follicle drug test procedures usually follow a similar pattern.
On paper, they’re meant to be precise and minimize the possibility of false positives. The first step is to collect a hair sample.
A technician will snip a small number of strands from the crown of a person’s head to do so, close to the scalp. This is where the most recent growth (and drug use) can be found. If hair on the head isn’t readily available, body hair can also be used as an alternative.
It’s not preferable, though, as it offers a different window of detection.
Once collected, the hair is sealed and shipped off to a lab for processing. This is where the real science begins. The hair sample undergoes treatments to remove external contaminants, to break down the hair follicles, and to isolate the traces of any drugs.
It’s worth noting the initial screen cutoff level is set at a point that it catches most (but not all) potential positives without being too sensitive. Using immunoassays, the initial test provides only preliminary insights.
A follow-up test that meets a predetermined confirmation cutoff level will establish the actual presence of a drug.
Guidelines for Substance Detection
How much is too much?
Depends on the drug in question and the company doing the testing. As a general rule of thumb, laboratories consider ng/mg when testing hair follicles, or nanograms per milligram. For the most part, the confirmation cutoff level is the same as the screen cutoff level.
This is because the tests differ in their accuracy. Generally, a drug panel will look for amounts in the realm of:
- 0.1 ng/mg for marijuana
- 0.2 ng/mg for opiates and amphetamines
- 0.5 mg/ng for cocaine
It’s probably not wise to ask an employer what the cutoff levels are – but to take adequate steps to prepare for hair follicle drug test procedures in advance.
We’ll get to that in a moment.
But what do these numbers translate to, in “real-world” terms? The literature is highly disputed:
On the one hand, laboratories and testing companies claim any sort of drug use will deposit metabolites in the hair (that they can conveniently detect for a fee). On the other hand, real-world studies often find conflicting results when comparing actual drug use with expected drug use based on the traces left behind in the body.
Ultimately, it’s a matter of metabolism, age, frequency of use, and fortune.
Timeframes for Different Substances
Every drug has a unique detection window. For hair testing, that window can extend from weeks to months.
Generally speaking, hair testing can detect drug use for up to 90 days. Your hair grows at a rate of half an inch per month, and a standard hair follicle test looks at one and a half inches of hair. If your hair grows faster, the detection period will be lower.
Marijuana and THC
THC (tetrahydrocannabinol) is the main ingredient of marijuana and it’s what a drug panel looks for. Marijuana stands as the most widely consumed (federally) illicit substance in the U.S., at approximately 18% of the population – so it’s a prime candidate for drug screening.
Even so, THC doesn’t bind to hair follicles as readily as other drugs, meaning the detection rate for occasional users is lower.
Regular, heavy use of THC is far more likely to result in a positive test. In rare cases, secondhand smoke caused by exposure can result in a positive result – but the screen cutoff level usually accounts for indirect exposure to THC.
Opioids and Amphetamines
Opioids aren’t like THC – they bind to hair quickly and linger for a three-month period. This class of drugs is well-incorporated into hair follicles, making even a single use of a substance easy to detect.
Amphetamines (including methamphetamine) are similarly easy to detect in hair follicle testing, albeit with a lesser frequency than opioids. They share a similar detection window to other drugs, but usually only show up on a hair drug panel with infrequent use. Using an amphetamine once is unlikely to cause a positive result.
Cocaine
Your body metabolizes cocaine fast. That lowers the window the drug has to bind to your hair – but if it does, it’ll probably linger for the same three-month timeframe as other drugs.
Interpreting Hair Test Results
After lab testing, results come back as positive or negative. A positive result indicates that drug metabolites were found above the established cutoff levels.
The screen cutoff level is the threshold at which a test comes back positive. It’s designed to ignore very low levels of exposure to a drug. The confirmation cutoff level gives the final verdict.
So, can you mitigate the chances of a positive hair follicle test?
That all depends on you…
Minimizing Substance Detection Levels
The most effective means of minimizing the presence of drugs in your hair is to avoid using drugs. If you can’t do that – or if you have a test looming – you’ll need to take steps to minimize the amount of a drug detectable in your hair.
How do you do that?
Firstly, you can secure an at-home hair follicle testing kit. This will give you an idea of the presence of drugs in your hair. Second, you can find detox shampoos online that will help you remove traces of substances in your hair.
These products should be combined with regular hair washing to achieve the best results.
One important caveat is medication: Some prescription drugs can interfere with test results. Adderall taken to combat ADHD, for instance, is an amphetamine. A person taking Adderall will likely receive a positive result from a drug panel.
You won’t get in trouble for your prescription meds, so it’s crucial that you disclose your medications before taking a drug test.
Abstinence and Detoxification
Wholesale detoxification can be a profound personal journey, representing a commitment to your health and your career. However, it’s unlikely to have an impact on hair tests.
What it can do, however, is prevent additional metabolites from binding to your hair follicles: Refraining from drug use and allowing your body to detox will lower the chances of a drug panel going over the cutoff level.
Hair Care Practices and Detox Shampoo
Bleaching and dying your hair will lower the probability that a drug panel will come back positive. For best results, you’ll want to combine a rigorous hair-washing schedule with a proven detox shampoo.
Such shampoos can be pricey – but they will provide the best results: The benefits far outweigh the costs of a purchase.
Get Ahead of a Hair Follicle Test
A hair test for drugs can identify them long after use.
If you’re facing a hair follicle test, the best thing you can do is prepare. Stay informed about procedures and timeframes. Plan ahead and embrace a lifestyle that aligns with your testing requirements.
And, when in doubt, reach for the detox shampoo.
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