How Far Back Does a Hair Follicle Test Go?

Reporting for a DOT drug test as a truck driver or other safety-sensitive employee means you’re going to either have to provide a urine or saliva sample, since those are the set testing methods in place.

However, there are a variety of other types of drug tests that can be given for other purposes. One of the most common is providing a sample via hair follicle. But like any sample, the question you probably have is how far back the detection window goes.

At Fleet Drug Testing, our team has the services and programs you need to stay compliant with any guidelines you may come into contact with. Whether it be a DOT test or some other drug test, we can answer any questions you may have. Contact us today to get started.

Hair Follicle Samples and Drug Tests

Under DOT regulations, the only methods for analyzing results come from either a urine or saliva sample. However, hair follicle testing is used for non-DOT drug testing purposes.

When a hair follicle drug test is conducted, the procedure usually goes forward in the following way:

  • A small sample of hair is typically collected from the person being tested. This sample is usually taken from the scalp, and it’s important to note that the length of hair required can vary but is often around 1.5 inches.

  • The sample is then sent for analysis at a laboratory.

  • In the lab, the hair sample is washed to remove any external contaminants, and then the internal part of the hair, known as the cortex, is analyzed for the presence of drug metabolites.

It’s important to keep in mind that hair follicle drug tests can detect a wide range of drugs, including marijuana, cocaine, amphetamines, opioids, and more. That said, the context and reason for testing is important, just in terms of being prepared. Generally, hair follicle samples are collected for the following purposes:

  • Job screening – Some jobs may use it for pre-employment checks.

  • Random workplace tests – Certain employers can do random drug tests to maintain a drug-free workplace.

  • After accidents – If there’s a work-related accident, employees involved might be tested for drugs.

  • Substance abuse programs – People in substance abuse programs may get regular hair drug tests.

  • Legal cases – Courts can order hair drug tests in various cases, like child custody disputes.

  • Probation and parole – Those under supervision may have to do hair drug tests.

  • DUI cases – Suspected impaired drivers, especially with a history of substance abuse, might undergo hair drug tests.

Regardless of the purpose of the test, submitting a hair follicle sample is an important part of complying with rulings. That said, being prepared for a test is very important to how your results may be interpreted.

How Far Back Does a Hair Follicle Test Go?

The main benefit of using a hair follicle sample on a drug test is that the detection window is longer than that of urine or saliva samples. Typically, it can detect drug use for:

  • Up to 90 days or approximately three months.

This is because the test analyzes drug metabolites that are incorporated into the hair as it grows. The specific time frame can vary, though, depending on:

  • Growth rate – People have different rates of hair growth. The standard detection window of approximately 90 days assumes an average hair growth rate. If your hair grows faster, the detection window might extend beyond 90 days, and if it grows slower, it may be shorter.

  • Hair length – The length of the hair sample taken can impact the detection window. Each half-inch of hair typically represents about one month of drug use history. Longer hair samples can provide a more extended history of drug use.

  • Drug use – The frequency and amount of drug use can affect the detectable time frame. Regular, heavy drug use may lead to a longer detection window, while sporadic or light use may result in a shorter window.

  • Type of drug use – Some drugs are more easily detected in hair samples than others. The detection window can vary depending on the specific drugs being tested.
  • Collection site – The location on the body where the hair is collected can influence the detection window. Hair from different areas may have varying growth rates and drug incorporation patterns.

  • Hair care products – Certain hair care products, such as shampoos or conditioners, may affect drug detection in hair. Some products claim to cleanse or strip drug metabolites from the hair, potentially altering the results.

  • Environmental exposure – In rare cases, exposure to drugs or drug smoke in the environment (passive exposure) could potentially lead to the presence of drug metabolites in hair, affecting the detection window.

Keep in mind that the usual timeframe for detecting drug use in a hair follicle test is around 90 days. However, this can vary from person to person due to factors like hair growth rate and other variables. So, if you have to submit to drug testing and are asked for hair follicle samples, it’s important to know how the process works and what your options are.

Let Fleet Drug Testing Help You

Regardless of why you need to undergo drug testing, Fleet Drug Testing is here to assist you. Our programs and services provide reliable solutions for drug testing and ensuring accurate storage and reporting of results. Whether you’re a truck driver or a company seeking to improve your drug testing procedures, we’re here to support you. Don’t hesitate to reach out to us today to get started.

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