Hair follicle drug testing detects evidence of drug use or misuse in a sample of hair. Drug testing can screen for the use of illegal drugs, as well as the misuse of prescription
medications, over-the-counter medicines, and legal substances including alcohol and tobacco. During hair follicle drug testing, scissors are used to remove a small sample of hair. Compared to other forms of drug testing, hair follicle drug testing offers advantages such as a long detection window and the ability to estimate patterns of drug use over time. The purpose of a hair follicle drug test is to detect evidence of drug use or misuse in a sample of a person’s hair. Drug use refers to the use of illegal substances. Drug misuse describes using prescription drugs in a manner that isn’t prescribed by a doctor or using legal substances in an unhealthy way. Hair follicle drug testing may be used over other types of drug tests because of its ability to show a longer history of drug exposure. This type of test
may be helpful when testing for chronic drug use or misuse, understanding long-term patterns of use, and confirming periods of abstinence. Hair follicle drug testing may be used in several ways: Hair follicle drug tests
identify drugs or drug metabolites in a sample of hair. A drug metabolite is a substance that is generated in the body as a drug is being broken down and eliminated. Once a drug is consumed, it enters the bloodstream and travels throughout the body. As the drug is broken down in the body, drugs and drug metabolites enter the core of the hair through the hair follicle, sweat glands, and oil glands on the scalp. Drugs and drug metabolites remain in the hair as it grows, which
occurs at a rate of about one-half inch each month. Some drug metabolites attach to melanin, the part of a hair follicle that gives hair its color. Hair follicle drug testing has a longer window of detection than other types of drug tests. While drug use and misuse may not appear in the hair until 7 to 10 days after drug exposure, once it enters the hair it remains for weeks, months, or even years. While testing hair can provide information about patterns of drug exposure, hair
follicle drug testing cannot detect current intoxication. How long drugs remain detectable in hair is called the window of detection. The length of the detection window varies based on a number of factors, including the amount and frequency of drug use or misuse and the rate at which the drug is metabolized in the body. Some drugs continue to enter new hair growth for months after a person’s last drug exposure. The window of detection also varies based on the
amount of hair tested. Although longer samples of hair can be tested for drug exposure over a longer period of time, a standard sample of hair from the scalp is 1.5 inches and provides information about approximately 90 days of past drug exposure. A hair sample taken from a different part of the body where hair grows more slowly may have a detection window of up to 12 months. Drugs that can be detected during hair follicle drug testing include: A hair follicle drug test may focus on detecting one specific drug in the hair or on detecting several substances in a hair follicle drug panel. One commonly used hair follicle drug panel looks for evidence of the use of five drugs or drug classes: marijuana, amphetamines, cocaine, PCP, and opioids. Hair follicle drug testing is used in workplace testing, legal and forensic
testing, medical testing, and for measuring the patterns of illegal and prescription drug use. The use of drug tests is impacted by federal, state, and local laws. Professional organizations advocate for the ethical use of drug testing, often emphasizing the importance of patient education and consent before conducting a drug test. Many parents consider using drug testing as a tool to prevent or confirm the use or misuse of drugs in children and adolescents. The
American Academy of Pediatrics advises against this practice, citing the lack of evidence that drug testing reduces drug use in children and adolescents, the potential for misinterpreting test results, and the negative impact on the relationships between parents and children caused by testing. A sample of hair can
be collected at home, at a laboratory, or in a medical setting. Hair follicle drug testing can be ordered by a doctor or an administrator of a program that requires drug testing. Hair follicle drug tests can also be purchased through retailers without a prescription. Can I take the test at home?At-home collection kits allow users to collect hair samples and mail them to a laboratory for analysis. At-home hair follicle drug test kits are available for purchase online and over-the-counter at a variety of retailers. Some at-home hair follicle drug tests look for only one type of drug while others offer test panels that look for several drugs at once. When considering the use of an at-home hair follicle drug test, it’s important to consider whether the company offers confirmatory testing for positive screening results. How much does the test cost?The cost of hair follicle drug testing depends on where a sample is collected, the type of hair follicle drug test ordered, and who is paying for testing. Patient costs may be covered by an individual’s health insurance or the organization requiring a drug test. In other cases, patients may choose to pay out-of-pocket for laboratory-based or at-home collection kits. Patients’ costs vary considerably, so it’s important to discuss questions about the cost of testing with the doctor, insurance provider, or organization ordering the testing. Taking a Hair Follicle Drug TestHair follicle drug tests are performed on a sample of hair, usually collected from a person’s scalp. Once collected, hair samples are sent to a laboratory for testing. In some cases, the collection of a hair sample will be performed by a trained professional to prevent tampering, contamination, or substitution of the sample. Before taking a hair follicle drug test, patients should ask the organization requiring drug testing about requirements for hair sample collection. Before the testAlthough there are no special precautions necessary before a hair follicle drug test, patients should inform their doctor of medications or supplements that have recently been taken. Patients should also inform their doctor of any recent hair treatments, including shampooing, as these may affect test results. During the testCollecting a sample of hair at a laboratory or at home involves cutting a lock of hair about the thickness of a pencil from the back of the head using scissors. During the collection process, the person cutting the hair should wear gloves to avoid contamination of the hair sample. Hair is collected as close to the scalp as possible, near the hair’s root, to provide information about recent drug use. A standard sample of hair is around 1.5 inches, although in some cases a longer sample may be collected for additional history of drug use and misuse. If patients don’t have sufficient hair on their scalp, hair may be collected from the face, armpit, pubic area, or another unshaven part of the body. Collecting hair is not associated with any risks, although some patients may experience embarrassment or anxiety during sample collection. After the testAfter a hair sample is collected, it is packaged according to instructions contained in the collection kit and sent to a laboratory for testing. There are no restrictions on activity after a hair follicle drug test. Once received by the laboratory, the hair sample may be washed prior to testing. Specialized methods of washing the hair sample remove some external contaminants, dirt, and grease from the surface of the hair. Drugs inside the hair are unaffected by washing. Receiving test resultsResults of hair follicle drug testing are generally available within a few business days after the laboratory receives the sample. Processing times vary, so patients may find it helpful to ask their doctor or the laboratory when to expect results. Depending on the reason for testing, patients may learn about their test results through a health care professional or the organization that required testing. Interpreting test resultsThe results of hair follicle drug tests may be reported as positive or negative. Positive test results indicate that a drug or its metabolite was detected in the sample of hair submitted for testing. Negative test results indicate that no drugs or drug metabolites were detected in the hair sample. Negative results suggest that a person didn’t consume the drug targeted by the test, that they used a drug outside of the test’s detection window, or that an insufficient amount of the drug was consumed to be detected in the hair. When interpreting results, it may be helpful to understand the laboratory method used for testing. Laboratory methods used in hair follicle drug testing are similar or slightly modified versions of those used in more common forms of drug testing, like urine drug testing. Laboratory methods used in drug testing are generally categorized as initial or confirmatory methods:
Although cutoff values for positive test results are not standard in all laboratories, the Society of Hair Testing, an organization that promotes research in hair testing, has proposed the following cutoff values:
Are test results accurate?Although hair follicle testing is an accepted form of drug testing, the results of this test can be affected by a variety of factors, including environmental exposures, hair composition, use of hair products, and even hair color. Additionally, some drugs attach to the hair more easily, like nicotine and heroin, while other drugs are more difficult to detect in hair. Factors that affect test results include:
Other concerns about the accuracy of hair follicle drug tests include:
Do I need follow-up tests?Follow-up testing after a hair follicle drug test depends on the test results and the purpose of drug testing. If only an initial test was performed, a confirmatory test may be ordered to confirm preliminary results. If a drug test result is positive, a health care provider may ask questions to evaluate the patient for a substance use disorder or addiction. The health care provider may ask about the impact of drug use or misuse on a person’s health and social obligations, any history of attempting to reduce or stop taking drugs, as well as whether the patient uses drugs in dangerous situations. Regardless of whether a patient meets the criteria to be diagnosed with a substance use disorder, treatment is available for drug use and misuse. Questions for your doctor about test resultsDrug test results can be difficult to interpret and patients can ask their doctor or the testing facility about the meaning of test results. Questions about test results include:
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Accessed July 6, 2021. https://www.fda.gov/medical-devices/drugs-abuse-tests/drugs-abuse-home-use-test Ask a Laboratory ScientistThis form enables patients to ask specific questions about lab tests. Your questions will be answered by a laboratory scientist as part of a voluntary service provided by one of our partners, American Society for Clinical Laboratory Science. Please allow 2-3 business days for an email response from one of the volunteers on the Consumer Information Response Team. How do you read a hair follicle drug test?The results of hair follicle drug tests may be reported as positive or negative. Positive test results indicate that a drug or its metabolite was detected in the sample of hair submitted for testing. Negative test results indicate that no drugs or drug metabolites were detected in the hair sample.
What are cut off limits on a hair follicle test?Screening cut-off levels followed the laboratory's standard practices for the 5-panel test: 1 pg/mg for marijuana, 500 pg/mg for cocaine and amphetamines, and 300 pg/mg for opioids; GC/MS confirmation cut-offs were: 0.30 pg/mg for carboxy-tetrahydrocannabinol (THC) metabolite, 500 pg/mg for cocaine and 50 pg/mg for ...
What does a hair analysis show?Hair analysis is done by evaluating hair structure and DNA from cells attached to the root of the hair. It can be used to find out if people are related. Forensic hair analysis can be done to help identify a person who may have been present at a crime scene.
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