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PDT-90 Hair Follicle Drug Test

  • Results processed in 5 days
  • Up to 90 day detection period
  • FDA Approved
  • Not for sale outside of the U.S. and its territories
  • Tests for 6 drugs: marijuana, cocaine, opiates, methamphetamines, ecstasy and PCP

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  • Information
  • Instructions
  • FAQ
how to get your hair drug test results for PDT90


A Hair Follicle Drug Test is an alternative to urine drug tests. The two primary advantages to a hair follicle drug test is that it goes back 90 days in history and it is virtually tamper proof. The "cleansing" shampoos widely sold on the Internet do not work. They clean the outside of the hair and do not affect the inside of the hair where a trace amount of the illicit drug is stored. If you need to find out what is going on in someone's life, a Hair Follicle Drug Test may be exactly what you need.

The PDT-90 Hair Drug Test from Psychemedics is very easy to use. Collect a small hair sample at home following the directions in the FDvideo how to collect a hair sampleA approved test kit, send the sample to the Psychemedics accredited laboratory in the envelope provided, then use your PDT-90 code number to obtain your results over the phone.
The presence of drugs in hair is based on a simple principle. Drugs which are ingested circulate in a person's bloodstream which nourishes developing hair follicles. As a person's hair grows, the new hair growth will have a trace amount of the drugs.

Trace amounts of drug metabolites become entrapped in the core of the hair as it grows out from the body at a rate of approximately one-half inch per month. These drug residues cannot be washed, bleached or flushed out and are stable over time. A laboratory analysis of the hair fiber from an individual will produce an accurate drug history for that person. The PDT-90 Hair Drug Test from Psychemedics goes back 90 days in history with a hair sample 1 1/2 inches in length.

It takes approximately 5 days for drugs start to show up in a person's hair. The new hair growth for the next 90 days will have a trace amount of the drugs and can be detected through laboratory analysis.

Your results are kept completely confidential and are for your use only. No names are ever used in the testing process. Your PDT-90 code number keeps all testing confidential and anonymous.

Test results are available 5 working days once the Psychemedics Laboratory receives the hair sample. Results are obtained by calling a toll free results hotline.

Each 1/2 inch of head hair provides a 30-day history of drug use. The standard for the industry is to test 1 1/2 inches, which provides a 90-day history of the donor's drug use. Bleaches, shampoos and second hand smoke (marijuana) have no known impact on test results. If you must retrieve scalp hair from a brush it can be used but the integrity of the test will be degraded. Hair collected from a shower drain will be rejected by the lab and no analysis will be performed.

Upon receipt, the Psychemedics Laboratory will melt the hair and perform an initial immunoassay drug test for the 6 drugs listed above. If any of those initial tests turn out positive, they will automatically confirm the results with a second test - a GC/MS laboratory analysis (the gold standard in drug testing).

The Psychemedics Laboratory needs the minimum equivalent of 90 to 120 strands of hair, 1 1/2 inches in length. If the test subject has short hair, then additional strands must be collected to meet the minimum laboratory requirements. (The lab needs a sufficient hair sample to melt to perform the tests.) However, with shorter hair the historic time frame will be reduced - 30 days for every 1/2 inch.

If you are interested in learning more about hair drug tests, please visit the Hair Drug Test section of our blog.

(If you would like more information on marijuana drug testing in particular, please check out our page solely dedicated to Marijuana Drug Test information!)

Instructions for PDT-90 Hair Drug Test

Hair Drug Test: Step 1: Please follow instructions properly so the test can be successfully processed and results may be provided.

Hair Drug Test: Step 2: Take the hair sample directly from test subject's head. We advise against taking hair samples from sources such as hair brushes since there is no guarantee the sample is from the hair follicle drug test subject.

A. Remove the materials contained inside the Hair Sample Collection Package. Your package should contain a white Sample Acquisition Card, a red Integrity seal and foil.

B. Fold the foil in half lengthwise and open, making a trough, and place aside in preparation for the collection.

C. Use a sharp pair of blunt-nosed scissors to collect the hair (Scissors not included).

D. Take the sample from the back/"crown" area of the head.

E. Find the area of the hair that is fullest and lift to expose the lower layer of hair.

F. Grasp a small lock of hair visibly equal to 1/2 inch wide and about one strand deep when held flat across your finger. (Sample cannot be tested unless quantity of hair is sufficient).

G. Cut hair as close to the scalp as possible for this hair drug test.

H. Put scissors down and grasp cut end firmly. Keeping the cut ends aligned, place the hair sample into the foil with the cut ends extending 1/4 inch beyond the slanted end of the foil.

I. Press the sides of the foil together, trapping the hair sample tightly inside. If hair is long, wrap the remaining hair around the foil. DO NOT CUT THE ENDS OFF THE HAIR!

J. NEVER cut hair that is in a braid for your hair follicle drug test. Undo the braid before you collect the sample. If the hair is short or curly it may help to wrap the foil around the hair prior to cutting. This will ensure proper alignment.

K. Insert the foil-wrapped hair sample into the Sample Acquisition Card with the root ends to the left.

L. Tear the PDT-90 Code Card from the Sample Acquisition Card. The Code Card contains your PDT-90 code number and our toll-free results number. Place it in a safe place, since you will need it to receive the hair drug test results.

M. Place the Integrity Seal on the Sample Acquisition Card once the hair sample has been inserted.

N. Date the Integrity Seal on the Sample Acquistion Card.

O. Read and initial the Sample Acquisition Card in the space provided.

P. Please retain your PDT-90 Code Card which contains your testing code number and the Psychemedics 800#.

Hair Drug Test: Step 3: Mail the collected hair sample.

A. Insert the Sample Acquisition Card into the first class postage-paid return envelope.

B. Seal the envelope and drop into any mailbox. No postage is needed.

Hair Drug Test: Step 4: Call Toll-Free for results.

Provided collection instructions are followed properly: Once Psychemedics receives the collected sample, their lab will test the sample for the presence of drugs.

TO RECEIVE TEST RESULTS, CALL 1-800-720-4247 with your PDT-90 code number.

Test results within 5 business days after lab receives hair sample.


Regardless of the length of hair sent in, results will only be provided for a 90 day period. Even if the hair can be analyzed for a longer time period, due to its length, only 90 days of results will be provided.


Frequently Asked Questions - PDT-90 Hair Drug Test

Differences Between Body and Head Hair

Differences Between The HairConfirm Express, Standard and PDT-90 Hair Drug Test

Q: Can body hair be submitted for this test?

A: No, it cannot. Only submissions of hair from the head will be accepted by the lab. Please keep this is mind when considering what hair drug test to purchase.

Q: Why did Marijuana (THC) show up negative?

In some cases, when the donor has used marijuana, a hair drug test, including HairConfirm, may be unable to detect the THC metabolite due to the fact that the metabolite was unable to bind with the hair shaft. This can be caused by the type/quality of the marijuana smoked/ingested, or by what it has been mixed with, e.g. tobacco. As a result, the result for marijuana may be negative. This is only the case with THC and not with the other illicit drugs (COC, Heroin..etc). In most cases with adults it takes smoking 5-6 full joints in order for enough of the drug to "stick" to the hair to show a positive- this is an average number. If the amount consumed by the individual was less than that it might not show up in a drug test.

In the case where a long term THC use is present (like medical marijuana) sometimes the individual’s body can create a masking agent that would hinder the marijuana in a drug test.

Statistics have shown that teenagers who have used marijuana are more likely to use other potentially more dangerous drugs, than those who have never used marijuana. So if you suspect the individual may be using marijuana it is important to remember that you are also testing for those illicit drugs.

Differences Between Body and Head Hair

Body hair and head hair cannot be mixed when you submit your sample. The different types of hair have their own advantages.

Body Hair

Can give you a longer drug history - a sample of 1.5 inches in length body hair can tell you up to 5-6 months of drug history (Please note - 1.5 inches from the root is as much hair as will be examined by the lab, regardless of how long the hair you submit is).

Head Hair

Easier to collect. A sample of hair at least 1.5 inches long will provide a 90 day drug history. No more than that 1.5 inch of hair will be analyzed by the lab though, so if you want to learn about drug activity going back further than 90 days, you may want to submit body hair for your hair drug test.

Differences Between The HairConfirm Express, Standard and PDT-90 Hair Drug Test

The HairConfirm Express and Standard home drug tests are the same except for only two factors - home to lab shipping method (the Express comes with a prepaid Fedex overnight mailer; the Standard comes with a prepaid first-class envelope) and processing time (the Express generally processes hair submissions in 2 business days while the Standard processes hair submissions in 7-10 business days).

The PDT-90 test has a few additional differences. First, body hair is not accepted by the PDT-90 lab. It is only accepted by the HairConfirm Standard and Express labs.

You also receive your results differently with a PDT-90 test. Results are obtained when you order a PDT-90 hair drug test by calling a toll-free number and providing your unique, anonymous and confidential code number to the operator, who then tells you whether the test was negative or positive. No names are ever used.

With the HairConfirm Standard and Express home drug test kits results are obtained online, also through a secure passcode. Results are given in a report format that can tell you frequency of use information about each drug tested for, with the exception of marijuana (which is reported as either positive or negative).