Why Would a Hair Follicle Test Have Inconclusive Results?

Q: My husband was recently hurt on the job (he works in construction). His boss had him submit to a hair follicle test the same day that he was injured. The test results came back inconclusive, so now my husband must submit to another test. Can you tell me why a hair follicle test would have inconclusive results? It was my understanding that these types of tests were much more reliable than standard urine drug tests. Is there a chance that the next test will have the same results? My husband finds the testing process a bit uncomfortable, so the sooner we get this resolved, the better.

G. Hardrow

Minneapolis, MN

A: It is a little misleading to say that a hair follicle test is more reliable than a urine drug test. In reality, each test is reliable for different situations. Urine testing is more reliable for detecting recent drug use, and hair testing is more reliable for detecting a history of past use. More than likely your husband’s hair test was rejected due to an insufficient quantity of hair. If his head hair was not long enough (most places require 1 ½ inches) they might consider a body hair collection for the follow up. If his hair is definitely long enough, it was probably due to the collector not taking enough hair for the test. Generally speaking, the lab requires 90-120 strands for a successful analysis.

Generally the collectors try to make the process as comfortable as possible. If the employer has requested a hair follicle test, it is unlikely that your husband will be able to do any other kind of testing. Just make sure he acknowledges that it is his second time getting the collection done, that way the collector can make a point to take enough hair for analysis. If you have any questions please feel free to contact one of our test experts.