Hair Testing vs. Urine Testing for CDL Drivers: What Is the Difference?

This is one of the practical differences drivers encounter while looking for a CDL job.

Some carriers require:

• A DOT urine drug test only

Other carriers require:

• A DOT urine drug test
• A separate carrier-required hair test

When a carrier requires both, the tests serve different purposes. The urine test is the federally regulated test. The hair test is an additional part of that carrier's hiring policy.

A driver may be willing to complete both tests. Another driver may only want opportunities with carriers that do not require hair testing.

That can be treated as a normal job-search preference. The driver can simply say:

The recruiter does not need to ask why. The recruiter can use that information when identifying which available carrier opportunities may fit the driver.

Carrier testing policies can change, and requirements sometimes differ by position, account, or location. Recruiters should provide the best current information available without guaranteeing that a carrier's process will never change.

Before allowing a newly hired CDL driver to perform safety-sensitive work, the motor carrier generally must receive a verified negative result from a DOT-compliant pre-employment drug test. A limited exception may apply when specific prior-testing requirements are met.

When the carrier orders a DOT urine test and a hair test, the urine test is the one used to meet the federal testing requirement. The hair test does not replace it.

DOT and non-DOT tests must be handled separately. The DOT test takes priority and must be completed before the non-DOT test begins.

This means the driver is not taking one combined test. The driver is completing:

• The federally regulated DOT test
• The carrier's additional non-DOT hair test

The carrier orders the appropriate tests and gives the driver the collection instructions. The driver generally only needs to go where directed and complete the process as instructed.

Urine and hair do not provide exactly the same information.

Urine testing is generally better suited to detecting comparatively recent drug use. Hair testing is generally used to examine a longer period of drug exposure.

A carrier that requires both may be using:

• The urine test to meet its federal DOT testing responsibility
• The hair test to apply its own longer-term hiring standard

The hair requirement is the carrier's choice. FMCSA does not require carriers to add a hair test.

That is why one carrier may accept a driver after a negative DOT urine result while another carrier may also require an acceptable hair result before completing the hiring process.

Drivers often hear two simplified statements:

• "Urine only goes back a few days."
• "Hair goes back 90 days."

Those statements describe the general difference, but neither one is a guarantee.

A hair test may identify a drug or drug metabolite above the laboratory's reporting threshold in the portion of hair examined.

It is generally used to look for a longer history or pattern of exposure. It is not a precise calendar, impairment test, or measurement of exactly how much someone used.

Different urine and hair results are not necessarily contradictory. The two specimens provide information about different periods, and the testing programs may use different panels, methods, and reporting cutoffs.

The previous guide, Before You Take a CDL Drug Test: What Every Driver Must Know, explains the urine collection process and what to do if there is a delay or the driver cannot initially provide enough urine.

In an ordinary DOT urine collection:

• The driver reports to the designated collection site.
• The collector verifies the driver's identity and explains the immediate steps.
• The driver usually provides the specimen in private unless DOT rules require a directly observed collection.
• The collector checks the amount, temperature, and general condition of the specimen.
• At least 45 mL is generally required.
• The collector divides the specimen into a primary bottle and a split-specimen bottle.
• The bottles are sealed, documented, and sent to an HHS-certified laboratory.

Once the collection has begun, the driver should remain at the collection site and follow the collector's instructions.

Drivers often call this a "hair-follicle test." In most workplace testing, however, the collector cuts the hair above the skin. The follicle beneath the skin is not removed and tested.

During an ordinary head-hair collection:

• The collector normally selects hair near the crown of the head.
• A small amount is cut as close to the scalp as practical.
• A common sample contains approximately 100–120 strands.
• The collector may take hair from more than one spot to avoid leaving a noticeable area.
• The sample is identified, packaged, and sent to the laboratory.

The laboratory ordinarily analyzes the portion closest to the scalp. For a standard sample of approximately 1½ inches, the laboratory generally describes the historical window as up to approximately 90 days.

Short head hair does not automatically mean that a hair test cannot be completed.

Depending on the laboratory and carrier program, the collector may:

• Collect shorter head hair if there is enough for the required sample
• Collect from multiple locations on the scalp
• Use hair from an approved body location when sufficient head hair is unavailable

Possible body-hair locations can include the chest, underarm, leg, or face. The acceptable location and amount depend on the testing provider's procedures.

Body hair has a different growth cycle from head hair. It should not be described as representing the same precise 90-day period. Its historical window is generally less exact.

If the driver does not have enough acceptable hair anywhere, the collector documents the situation and the carrier determines what happens under its own policy. The carrier may have an alternative procedure, or it may determine that its hair-testing requirement cannot be completed.

Because hair testing is non-DOT, an inability to provide a hair sample does not automatically become a DOT refusal or Clearinghouse violation. It may still affect whether that carrier continues the hiring process.

The driver should simply appear as directed and allow the collector to determine whether an acceptable sample is available.

Ordinary shampoo, hair products, hair dye, or bleaching does not automatically prevent the collector from taking a sample.

Cosmetic treatment can affect hair differently depending on the product, the condition of the hair, the substance being tested, and the laboratory method. Major laboratories use preparation, washing, confirmation, and review procedures intended to produce reliable results.

One major workplace laboratory reports that normal treatments, including dyeing and bleaching, typically did not change the final reporting category in its testing. That finding should not be treated as a guarantee for every sample or every testing program.

The driver does not need to diagnose whether the hair can be tested. The collector and laboratory handle that determination.

Marijuana remains part of federal DOT drug testing.

State legalization does not change the federal DOT result. The same is true when a state permits recreational marijuana or a doctor recommends medical marijuana.

Under DOT rules, an MRO cannot change a confirmed marijuana result to negative based on:

• Legal recreational marijuana use under state law
• A state medical-marijuana recommendation
• Use of a CBD product
• Use of another hemp or marijuana-related product

CBD products are not regulated consistently and may contain enough THC to produce a confirmed marijuana result. DOT warns safety-sensitive transportation employees that claiming CBD use is not a legitimate medical explanation for a confirmed DOT marijuana positive.

A carrier's non-DOT hair policy may also prohibit marijuana. The exact non-DOT review process depends on that carrier's program, but state legalization does not require a carrier to ignore its lawful employment-testing policy.

A recruiter can help the driver understand the type of testing a carrier currently requires.

A recruiter can ask: