Hair drug test or hair follicle testing is a practical, accurate and now commonly used way to know drug abuse in a person. Its effectiveness is way better than urine test or any other test to find out drug abuse. But how far back does a hair follicle test detect drugs?

A hair follicle test can detect drug use up to 90 days after use. On the other hand, a urine test can detect drug abuse for about 30 days only. So a hair follicle test is the right choice to make if you want to check drug use for the past three months. 

Now relating to the hair follicle test, other questions also arrive, like how much does it cost, how it works, how it can be taken, can it tell how much drug abuse is done, etc. So let’s get answers to all these questions!

What is a hair follicle drug test?

A hair follicle or hair drug test checks the illicit drug use or misuse of prescription drugs. In the hair drug test, a small amount of hair, like the size and width of a pencil, is used to check drug abuse. 

Through different kinds of chemical and medical ways, the use of drugs is determined, whether positive or negative. 

What kind of drug can be detected through a hair follicle test?

A hair follicle test can determine the use of the following drugs – 

How far back does a hair follicle test detect drugs?

As mentioned earlier, a hair follicle test can determine drug use in the last 90 days, and it is way better than a urine test which can only check drug use in the previous 30 days.

However, theoretically, it is estimated that hair follicle tests can check the use of drugs over the last three years. As hair grows at 0.5 inches per month, it means if you have 18-inch hair length and consumed drugs three years ago; then chances are you can test positive in the hair follicle test.

However, in a hair drug test, only 1.5 inches of hair from the root are taken to test.

How does a hair follicle test work?

In a hair follicle test, 1.5 inches of your head hair (which is the width of your pencil) from the root are taken. Then the test happens on the hair to find whether you have taken the drug in the last 90 days or not. 

A test named ELISA is done first to check the hair samples. A negative result comes 24 hours after the test. If any positive result comes, then the testing happens again (named as GC/MS) to check the specific drug use.

Actually, when you consume any drugs, it mixes into the bloodstream. And for a hair to grow, the follicle has blood vessels that carry blood for hair growth cells. So this way, through blood, the drugs are carried into hair follicles. And that’s how drug abuse is detected through hair follicles tests.

Can the hair follicle test tell the date of drug abuse?

No, the hair follicle test cannot tell the exact date of drug abuse. It can only tell if any person has used drugs in the last 90 days and also which drug has been used.

How much does the test cost?

Generally, it cost from $65 to $85 for an at-home kit. But if you get the test done from a laboratory, then it will cost you between $100 to $125. A hair follicle test is expensive but gives an accurate result for drug use in 90 days compared to a urine test. 

If you’re an employee, you will get compensation for the time used in doing the test either by yourself or by a lab. 

How accurate is the hair follicle test?

Hair follicle tests are very accurate, and to increase the accuracy, hair is even washed and tested to check for any environmental contamination. Then the tests happen, and it gives accurate results only. 

Also, even if you use hair products, dye, or wash your hair with any shampoo, the results will not change. 

For more accuracy, two hair follicles tests are done; First is ELISA, which tells whether the drug use is negative or positive. Then to confirm the positivity and which drug was used, another test named GC/MS is done. 

Can someone cheat the hair follicle test?

It is almost impossible to cheat on the hair follicle test because the drugs’ metabolites remain in the hair. So, even if you use any shampoo, hair product, or dye, it will not alter the drug metabolites in the hair. 

And the test will show positive results if the presence of drugs is in the hair.

What are the pros of the hair follicle test?

  • The test provides a long detection period of up to 90 days. 
  • No one can alter the hair follicles even after the use of anything on the hair. 
  • It has a high level of accuracy. 
  • If the test is positive then, the test is done again to confirm the positivity. 
  • The test is great for offices to check the employees, schools, colleges to check the students

What are the cons of this test?

  • The hair follicle test is expensive. 
  • It cannot tell the date of abuse. 
  • The processing time of the test is time-consuming. 

Bottom Line

A hair follicle test has come as a great and accurate way to check drug abuse. Although it is expensive, it still gives accurate results even after drug abuse of the last 90 days. 

We hope you get the satisfactory answer to your question, ‘How far back does a hair follicle test detect drugs?’

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