The Ultimate Hair Drug Test FAQ

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To see our tests, check out our hair drug test page.

What drugs are tested for by the hair drug test?

The drugs tested for by the PDT-90 hair follicle drug test are marijuana, cocaine, opiates, methamphetamines, ecstasy and PCP. The Express, Standard, Legal Workplace, and the Illegal & Prescription hair follicle drug test detect marijuana, cocaine, opiates, amphetamines, methamphetamines, ecstasy and PCP. So, the only drug type the PDT-90 does not test for that the other kits do is amphetamines.

How much hair is needed for a hair drug test?


The minimum amount of hair needed for a hair drug test: a half inch. A half inch of hair represents about a 30 day drug history.

The maximum amount of hair needed for a hair drug test: the lab will only analyze the most recent inch and a half of hair (giving you a 90 day drug history). However, when you submit your hair sample, do not shorten the hair you provide. If your hair is 8 inches long, submit the entire 8 inches in length. The instructions in your kit will explain how to wrap the excess hair around the collection foil.


The thickness/width of the sample you provide should be 120 hairs or so. This is about the diameter of a pencil.

How do you collect the hair?

You can collect the hair from multiple places on the head. You must cut the hair from as close to the scalp as possible. After you cut the hair, you place it in a collection foil with all the root ends arranged together.

If you for some reason have a sample of hair that cannot be arranged with all the root ends together, the laboratory may still analyze the sample, but following the collection procedure carefully is still suggested.

The root ends being arranged together is NOT important if the hair sample is less than an inch and a half long. The reason the root ends must be arranged together if the hair is longer is because upon receiving the sample the laboratory will cut the hair down to an inch and a half in length.

How long does it take drugs to enter the hair?

It takes about 5-7 days for the hair affected by the drug use to grow out above the scalp. In the case of body hair, it takes longer.

How do you properly package long hair?

If the hair is long, you can wrap the remaining hair around the collection foil.

Can I submit hair collected a while ago?

Yes (but not too long ago). For example, you can collect the sample before the test arrives or a month ahead of time.

Can I use hair from a hairbrush?

We do not recommend this for a number of reasons. Hairs from a hairbrush may not all be from the same time period or person. It is also nearly impossible to arrange them so that all the root ends of the sample are together. If the sample is not properly collected, the lab may be unable to analyze it (and in such cases, Home Health Testing does not accept the return of the product). We recommend that the person you are hair testing knows they are being tested.

Can I submit just one hair?

Unfortunately, you may not. The sample size is about 120 hairs (please see above for more information).

Can I use body hair?

You can submit body hair in the following tests: the Express Hair Follicle Drug Test, the Standard Hair Follicle Drug Test, the Legal Workplace Hair Drug Test Kit, and the Illegal & Prescription Hair Follicle Drug Test.

The only test that does not accept body hair submissions is the PDT-90 Hair Follicle Drug Test.

How do I collect body hair?

Be sure to collect hair that is at least half an inch long. You can collect hair from the underarms, arms, legs, or chest.

What time frame does body hair represent?

A sample of body hair an inch and a half in length will give you a history of about 5-6 months, as body hair grows more slowly than hair on the head. This also means that it takes longer for drugs to grow out into the body hair than the head hair.

What is the difference between Standard and Express versions of the hair follicle drug test?

The differences between the Standard and Express versions of the hair follicle drug test are just the amount of time it takes for the lab to process the sample, and the type of prepaid shipping mailer you receive with your kit to get the sample to the lab. You can see the differences between the hair drug tests on this chart here.

Can the test hold up in court?

This is a somewhat tricky question. First, the only test that can hold up in court is the Legal Workplace Hair Drug Test Kit. This is because, unlike the others, it is NOT anonymous. It includes a Custody and Control form and all results are reviewed by a Medical Review Officer. This is why it is recommended for workplaces. The test has been used in custody cases, but it is highly recommended that one consults their lawyer before purchasing the test to find out if the test will hold up in court in one’s particular state or situation.

Why did Marijuana (THC) show up negative?

In some cases when donors use marijuana, the metabolite is not detected by a hair test because it didn't bind with the hair shift. This may be due to the type/quality of marijuana ingested or what is was mixed with (tobacco for example). This is only the case with marijuana and not with other illicit drugs. According to HairConfirm who manufacturers these tests, it takes smoking 5-6 full joints in most cases, for the drug to stick to the hair shaft in order to get a positive result. If someone consumed less, it may not show up on a drug test.

Do detox or masking products work?

The HairConfirm Lab tests the actual molecules embedded in the hair shaft, therefore no external or topical source or agent can alter the test results. None of these so-called detoxifying shampoos or products can alter a forensic hair test performed in a laboratory, so therefore these tests are basically cheat proof.

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