How Long Does Hair Drug Tests Show Results?
18 January, 2023
A hair drug test is a screening method for checking alcohol and illicit drug use through hair strand samples. Substances enter the hair follicles and appear until 7 to 10 days after initial exposure. Once they enter the hair, they remain traceable for up to 90 days. Thus, they provide a long detection window for determining drug and alcohol use. Its uses prove invaluable in monitoring alcohol consumption in hospitals, rehabilitation facilities, workplaces, and legal cases.
Illicit drug use has detrimental effects on health and safety. It can lead to addiction and severe impairment of vital functions, which may result in accidents. In addition, people who are dependent on drugs may try to hide their condition. However, it can manifest in several ways, like appearance, behaviour, and actions. Employers or healthcare providers may request a hair test to confirm suspected drug use. This article will discuss how a hair test works, its uses, and various considerations.
How a Hair Drug Test Works
A hair drug test identifies the parent drug or metabolites. Portions of drugs and alcohol in the bloodstream enter the hair through passive diffusion. Additionally, they embed in the strands as the hair grows, providing a long detection window. Therefore, rather than hours or days, a hair test covers months. It can pick up consumption patterns, which can help determine a history of drug use or abstinence. The sample collection process is also easy and non-invasive.
To perform the test, a technician collects a 100mg hair sample, approximately 90 to 120 strands, at the scalp. The sample is secured in foil for proper documentation and transport for laboratory analysis. Since the procurement is done openly, it minimises the probability of adulteration or tampering. Moreover, hair tests are accurate as external contaminants like shampoo or hair products do not affect the results. However, drug types, dosage, and hair colour may affect drug concentrations.
Substances generally enter the hair through passive diffusion at the base of the hair follicle. More findings also suggest that drugs may enter during the hair shaft formation and after the hair has emerged from the skin. Furthermore, hair growth varies between individuals. Thus, a hair drug test can detect substances taken after 7 to 10 days. A 1.5-inch hair sample can trace drug use for 90 days before testing.
Drug detection in hair depends on several factors, such as the type of drug, the route of administration, the amount, and cut-off levels. A hair test can trace the following substances and their metabolites:
- Opiates (codeine, oxycodone, hydrocodone, morphine, methadone)
- Amphetamine and methamphetamine
- Phencyclidine (PCP)
- Cannabis or marijuana
- Methylenedioxymethamphetamine (MDMA)
Uses of Hair Drug Tests
The standard drug detection methods are urine or blood sampling. A urine test is helpful in various settings because of its fast turnaround results. However, a hair drug test is appropriate in certain situations. Due to its long detection period, it is vital for determining long-term consumption patterns. Treatment centres may use it to assess the history of drug use. Likewise, a workplace may request a hair follicle test before hiring an applicant.
Since a hair test can detect drug use for the past months, employers use it to screen a job candidate. It can reveal a person’s history, which is difficult to circumvent. It can show a positive result for a chronic user, who may temporarily abstain for several days. Moreover, a workplace may also utilise a hair test randomly during employment or specific cases. However, industry regulations can differ when they allow a hair test for drug screening.
A hair drug test is also vital in legal systems, such as custody cases. A judge may order drug testing based on the alleged frequency of use. In custody cases, it is common for both parties to agree to hair follicle testing. Similarly, people under probation for drug-related offences, like impaired driving, are subject to routine drug inspections. A hair test may be used with other methods during the probationary period.
- Provides a long detection window than hair, oral fluid, or blood testing
- Non-invasive collection process and easier to store and transport
- Difficult to cheat or adulterate the test
- The lab can retest the same sample multiple times, allowing greater accuracy
- Differentiates between occasional incidents and addictive behaviour
Considerations of Hair Drug Tests
A hair drug test is one of the easiest and most convenient drug screening methods. However, it has a few drawbacks. While hair samples trace long-term use, they cannot detect recent consumption. Therefore, companies that want to monitor substance impairment may use other screening procedures, such as urine analysis for drugs and breath tests for alcohol. This is because it takes time for hair to grow and drugs to show up in a hair follicle test.
The detection period is one of the essential factors to consider in choosing a test method. It also depends on the purpose of the test, including monitoring abstinence, identifying substance use disorder, or detecting current impairment. However, it could trace drugs that a person no longer actively uses. Therefore, it poses a disputable area in drug testing. Workplaces and hospitals may need to discuss with concerned individuals in case of positive results.
Hair drug tests are more expensive and have a longer processing time. Thus, most workplaces use urine or oral fluid testing. Additionally, other concerns about hair test accuracy include test result interpretation and detecting low-level use. It is more challenging to determine when drug exposure occurred due to metabolites in sweat. Lastly, it requires high cut-off levels to get a positive result and to identify drug abuse.
Factors Affecting a Hair Follicle Test
- Chemical treatments – bleach or hair dyes can damage the hair shaft and expose it to possible contamination.
- Hair colour – drugs can bind more easily to darker hair colours, leading to higher concentration.
- Area of sample collection – if head hair is unavailable, body hair can be an alternative.
- Growth rate of hair
A hair drug test is efficient for detecting long-term drug use to establish a person’s consumption behaviour. Illegal drugs or misuse of prescription medications are traceable in the hair within 7 to 90 days. Thus, it is often applied to screen candidates for safety-critical jobs or to comply with state or industry regulations. Moreover, it is a convenient and non-invasive testing process that can provide high accuracy. It also gives a better understanding of a patient’s history in recovery programs.
Drug testing is essential to keep workplaces or other public areas safe and healthy. Companies or individuals may use test kits to screen for drug or alcohol use. In particular, hair testing can provide detailed information that other methods cannot give. However, a correct sample collection process is vital to get the most accurate results. Understanding how different methods work and how drugs affect the body can help pick the most suitable method.