Hair Follicle Drug Testing Frequently Asked Questions

If you need a hair drug test, first you need the facts: how far back does it go? What drugs can be detected? Body hair vs. head hair vs. no hair at all.

Jared Rosenthal
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So, your boss asked you to get a hair test. Or maybe your ex. Or your parent. Or your future employer. You have heard all kinds of rumors about what this test can detect and how far back it can go in those detections.

But what is true? And what is false? Let's take a few moments to dispel the rumors, the myths, and clear up any confusion surrounding drug hair follicle testing, and while we're at it, we'll explain the truths too.

How long do drugs stay in your hair?

Hair follicles grow at a rate of approximately half an inch per month. In theory, if your hair was 18 inches long, and you tested the far ends of the strands, then you could find drugs consumed more than three years ago.

Hair drug testing goes back much, much longer than urine drug testing. When you ingest drugs, it goes into the hair follicle, and then into the strands themselves, where they stay, pretty much forever.

How far back can the hair follicle test go to detect drug use?

The hair follicle drug test, when using the standard 1.5 inches of hair, can detect previous drug use up to 3 months. If a longer piece of hair is selected, the drug test results can go back much further (in fact, years further) to detect drug use.

How long does the hair need to be for a hair follicle drug test?

There is only one standard for this test, which is 1.5 inches of hair, cut from the root. The non-root end is discarded. We recommend that you watch the technician perform the test and ask them to cut off and discard the length beyond the first 1.5 inches. This request ensures that the 1.5 inches equate to approximately three months of history.

What drugs can be detected in a hair drug test?

A hair drug test can detect the presence of virtually any drug or alcohol substance. Until recently, there were only a few drugs that could be tested through the hair, but the list is growing. Below is the expanding list of drugs that can be tested via hair follicle:

  • Cocaine
  • Marijuana (THC, cannabinoids)
  • Amphetamines (including methamphetamines)
  • Basic Opiates (heroin, morphine, codeine)
  • Expanded Opiates (hydrocodone, oxycodone)
  • PCP (Angel Dust)
  • Benzodiazepines (Xanax)
  • Methadone
  • Barbiturates
  • Propoxyphene
  • Demerol
  • Tramadol
  • Fentanyl
  • Sufentanil
  • Synthetic Marijuana
  • Ketamine
  • Buprenorphine (Suboxone)
  • Zolpidem (Ambien)
  • Alcohol

Can you test for different drugs at one time?

Yes. There are more than one dozen different Hair Testing Panels. A panel is the medical term for the type of drug screening. Think of the word panel as a package or a combination. Drug panels give you (or the person requesting the drug test) the option to include alcohol in the test, expanded opiates, synthetic drugs, Benzodiazepines, and more.

A few of the most commonly requested hair follicle drug testing panels include:

Can body hair be used for the hair follicle test?

We can test underarm, leg, or chest hair. Occasionally, beard hair can be used as well. And, no, we cannot get the hair from any other place on your body other than those previously mentioned!

Does body hair hold drug residue longer than head hair?

There is much debate about the pace at which body hair grows. Many people are concerned that an inch and a half of body hair will retain drug residue for a much longer period if the body hair grows much slower than the head hair.

The reality is that body hair and head hair grow at the same rate. The difference is that body hair tends to stop growing at a shorter maximum length. In both head and body, new hair replaces dormant strands and pushes them out.

Think about how you naturally shed hair. Shedding happens because a new hair pushed out the old one, which stopped growing and became dormant. When a hair is dormant (i.e., not growing), no new drug deposits can get into it. It can stay there 1 to 4 months, so in theory, head OR body hair can reveal drugs that go back further than 90 days, depending on the person. However, only 10 to 15 percent of your strands are in this dormant phase, so the risk is minimal.

On the other hand, there are many anecdotes (and a few labs) that report that body hair can pick up drugs for up to 12 months. Although there are no scientific studies that have shown this conclusively, you'd be wise to consider it when thinking about how to interpret the results.

The bottom line is: the 90-day mark is an educated estimate, but there is no calendar in your hair. Accordingly, a positive result doesn't indicate the dates that the drugs were used. In conclusion, your hair retains your drug use history, but not in the same way that, say, an internet browser retains your search history.

What if I have no head or body hair?

Sometimes Health Street gets calls from people who want a hair drug test, but they have no head or body hair. A guy recently told us, "I shave from head to toe." Well, how did he think we were going to perform the test? We are still trying to figure that one out! The bottom line: no hair means you can't get a hair drug test.

Does the hair follicle drug test work if I'm an infrequent user?

Yes, the hair follicle drug test works regardless of how often one uses drugs. The frequency of drug use does not impact test results. It is the period in which the user used drugs that determines the outcome of the hair follicle drug test. Whether a person used once or 50 times in a three month period, the hair follicle drug test will indicate that drug use.

Can I "cleanse" my hair of drugs so I will pass the hair follicle drug test?

Contrary to popular belief, there is no way to cleanse your hair of any drug substance. Drugs enter your bloodstream and thus, become embedded in your hair, and it stays there until that hair is removed from your body.

Can secondhand smoke make me fail a hair follicle drug test?

No. While secondhand smoke is inhaled, there is not enough of the substance that causes the "high" (THC) in secondhand smoke to cause you to fail a drug test. This "passive exposure" will not impact your hair follicle drug test results.

Is hair follicle testing accurate?

Yes, hair follicle testing, is, indeed, accurate. In fact, it is more accurate today than it ever has been.

Hair Drug Testing Facts and Myths Infographic

Hair Follicle Drug Testing Frequently Asked Questions - infographic
Jared Rosenthal

Jared Rosenthal

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