Fail Your Hair Drug Test

You May Fail Your Hair Drug Test: 4 Warning Signs

While most people are not as at much risk as they believe there are, there are certainly some warning signs that you are likely to fail your hair drug test that you should be aware of.

1. Sign You May Fail Your Hair Drug Test: Very Little Clean Time

Your clean time is the amount of time from your last use of drugs and the day that you have to submit your drug test sample. Anything less than 90 days is something to begin becoming concerned about.

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Somewhat counter-intuitively, if you were to have only used drugs once and your one and only usage leaves less than until your hair drug test, you’re probably okay since the hair containing the drug metabolites hasn’t grown above your scalp area yet.

However, that is the exception (and quite a rare one at that). Everyone else should be focused on clean time.

If it’s been more than 90 days, you’re very likely to pass. The test itself is designed to only sample hair that has grown in, in the last 90 days (1.5 inches of hair to be exact).

If your clean time is less than 90 days but still relatively long – say maybe 70 or 80 days – you still have options.

For instance, you might cut your hair in order to only submit a sample that only offers a 70 or 80-day sample. Cutting your hair to 1.25 inches would likely be an adequate length for most testing facilities and it would strip several days off of your drug testing window.

Anything time shorter than that begins to increase the chances that you will fail your hair drug test.

Fail Your Hair Drug Test

2. Sign You May Fail Your Hair Drug Test: Frequent Drug Use

Drug testing labs have admitted in research papers that infrequent marijuana use is likely to go undetected in a hair drug test. THC metabolites simply don’t bind as well to the hair as do other drugs and infrequent marijuana usage tends to give unreliable results.

The more frequently that you ingest THC the higher the chances are that you will fail your hair drug test.

3. Sign You May Fail Your Hair Drug Test: Drug Dosage

What we’re really looking at here is the amount of THC that you are putting into your body. The more potent the source the less it takes to get a similar dosage.

In other words, smoking a relatively small amount of medical grade marijuana can result in a THC dosage similar to smoking a considerable amount of some dirt weed you smoked at a Full Moon Party in Thailand.

When factoring your risk for failing your hair drug test, always keep in mind the relative dosage of THC.

4. Sign You May Fail Your Hair Drug Test: Long History of Use

Not just the frequency of use (Sign #2) but the length of usage also plays a major factor in whether or not you will fail your hair drug test.

Some evidence seems to suggest that someone who smoked marijuana for 2 years daily and then suddenly quits 80 days before the test would be at a greater risk of failing a hair drug test than someone who never smoked marijuana but smoked for 10 days during the 90 day detection window.

Whether long-term usage causes a buildup of THC metabolites that are released long after the user quits using or the person’s body simply becomes more efficient in depositing THC metabolites into the hair is unknown but it does seem to play a factor in drug detection.


So if any or all of the above apply to you, will you fail your hair drug test? No. Each factor increases the risk of a positive test result but they are just that, risk factors.

They also do not take into account measures you can take on your own to reduce the amount of THC metabolites in your hair. For instance, if you follow the steps in How to Pass a Hair Follicle Drug Test, you could have little clean time, be a long-term, frequent user smoking the best weed out there, and still pass. It’s just a matter of understanding the risks and applying the correct solutions.