Home Uncategorized • How does the hair test work?

How does the hair test work?


Whatever you take into your body often stays in the body for a long time. This is more common with certain types of drugs. Although our hair is not alive, there are certain parts that are alive such as follicles. If illicit drugs such as cocaine, marijuana, methamphetamine, alcohol or heroine are in our bodies, the follicle deposits will show traces of these drugs or some metabolites that indicates the existences of drugs in the body. Therefore, your hair can act as signature for presence of drug as long as your hair continues to grow.

Because your hair will keep on growing over time, sample will help to detect the presence drug use from the past weeks or months. Hair unlike saliva, blood or urine, it is very stable and can easily be processed, transported and stored, and it is hard to adulterate it. Hair can also help to detect chronic drug use. Hair drug test is more accurate compared to urine test, and cannot be manipulated by any cleansing product.

How to Obtain and Prepare a Specimen

Hair specimen is collected by removing a small amount hair. A hair drug test uses the hair sample of about 1.5 inches long. To get accurate results a minimum of 3 hairs should be used for each test. It is then washed to eliminate any chemicals or dirt. Some hairs have chemicals such as shampoo and other hair treatments, or contaminated with tobacco, which may affect the accuracy of the test. Once the cleaning has been done melanin found in the hair will then be processed.

ELISA Screen Testing

Hair samples are then screened by using ELISA (Enzyme Labeled Immunosorbent Assay) technique. This test is used to detect any traces of drugs or their metabolites. A number of special anti-bodies are mixed with sample to identify the presence of drug. Each antibody will bond with a different drug or even it’s metabolites. An automated machine is used to detect the bonding and identify the drug present in the hair.

A Further GC/MS Testing might be required

In a situation where ELISA testing result is positive, a further testing should be carried out. A GC/MS (Gas chromatography & Mass Spectrometry) test should be done in order to identify any specific markers present in the hair. This test is also used to eliminate any false positives. Gas chromatograph is used to purify the specimen. A comprehensive spectrum of chemical composition in the specimen is identified by mass spectrometer testing. Presence of spikes of the spectrum indicates the presence of specific drugs in the hair sample.

Advantages of Hair Drug Test

• Hair testing can detect drug use several months after ingestion. It is said that the hair grows at an average of one-half inch every month. This strand of hair can indicate the signs of drugs used for the last three moths.

• Hair drug testing is more convenient and less embarrassing compared to urinalysis. The sample can easily be collected and transported to the Lab. Hair sample does not required any refrigeration to be done for testing.


Leave a Reply

Your email address will not be published. Required fields are marked*