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Hair Follicle Testing

What You Need to Know

Hair follicle testing for truck drivers is an extra effort to keep our highways a safer place for all drivers! Because moving freight in tractor-trailers can be extremely dangerous in the wrong hands, carriers want to make sure they hire drug-free CDL truck drivers who will drive these large vehicles safely.

Hair Follicle Drug Testing for Truck Drivers

Hair follicle drug testing for truck drivers is an extra effort to keep our highways a safer place for all drivers! Because moving freight in tractor-trailers can be extremely dangerous in the wrong hands, carriers want to make sure they hire drug-free CDL truck drivers who will drive these large vehicles safely.

What’s changed?

According to, “On December 4, 2015, the FAST Act transportation bill was signed into law by President Obama. Among other provisions, it allows for hair follicle drug testing as a DOT-approved method, but not until the Department of Health and Human Services establishes guidelines for testing, which must be completed within a year.”

As of right now, carrier companies can’t use hair follicle drug testing to satisfy Federal DOT drug testing requirements. In other words, you will probably have to perform a urine test, or urinalysis, too. However, trucking companies can make passing the hair follicle test a requirement for hire.

What is hair follicle testing?

Similar to providing a urine sample, your future carrier company may make an appointment for you at a hair follicle testing facility. Here, a lab specialist will cut off a small portion of your hair for testing (typically, the first inch and a half of hair nearest the root will be tested).

Hair follicle testing looks for two things: the presence of a drug and something called a metabolite that carries a record of the drug.* When a person consumes drugs, the drugs enter the bloodstream. The blood then metabolizes, or processes, the drugs and produces a metabolite (kind of like a genetic record of the drug used). Hair follicles use blood for nourishment, and the presence of drugs and the metabolites are absorbed into the hair follicle. As hair grows it passes a genetic record of drug use through the follicle into the hair strands.

While the term “hair follicle testing” makes it seem like your hair roots will be tested (because that’s pretty much all a follicle is!), your hair strands are what will be considered.

Frequently Asked Questions

How far back do hair follicle tests look?

While there’s still some debate about detecting illegal substances in hair as far back as a year, the typical result window is up to 90 days. Trucking Truth says, “Hair follicle testing can detect traces of illegal substances from as recently as 10 days to as far back as 90 days (using a typical 1 1/2-inch hair sample) from their use or ingestion, which is the standard length many companies will use.”**

What if I don’t have any hair?

No problem! Body hair is usually acceptable if the hair on the head is too short, but only if it meets length requirement (typically 1.5 inches). Hair taken from the chest, leg, or armpit is a possible alternative at some testing facilities. The negative side to this is “a driver who does not have enough hair on their body to be tested may be classified as a “refusal” and denied employment by a particular company.”**

Do hair products hinder the hair follicle test?

Additives and products like gel and styling cream don’t actually alter the hair strand but put a temporary layer of material on the outside. Hair products such as shampoos don’t change the hair’s ability to retain the proof of drug use either. Bleached hair, on the other hand, is less stable for retaining the proof of drug use. Bleached or dyed hair doesn’t necessarily disqualify drivers from receiving a hair follicle test, though.*

What about second hand smoke?

According to, “environmental exposure (such as second hand marijuana smoke) does not cause a positive hair test.” Remember, hair follicle tests look for both the presence of the drug and the metabolite that your body generates when you consume drugs. Even if you were to get smoke in your hair, your body would not produce the metabolites that the test is looking for.*

Who can see the test results?

Hair follicle test results are not posted for the public to see. In fact, “results cannot be reported to the DOT as a failed test, nor can they be shared with other companies.” You should be aware, though, that “a failed hair follicle drug screen CAN and MAY be reported on your DAC report as a failed test, depending on the trucking company’s policy.”**

Keeping the Roads Safe

While this isn’t a national requirement yet, many carrier companies are jumping on board with hair follicle testing. At the very least, you should be aware of the testing that may be involved as a CDL truck driver. These tests are put in place to save lives and keep the roads safer for everyone. After all, truck drivers have a large responsibility on their hands and should make sure they do all they can to protect fellow drivers on the nation’s highways!