Hair Follicle Drug Test Facts

Hair follicle testing is one of a few common tests for recent drug use, alongside urine and saliva tests, used frequently by employers as part of an applicant screening process or to determine if current employees are engaging in illegal drug use while under contract by the company.

How Does It Work?

• Using a small hair sample from the person being tested, the hair follicle drug test relies on drug-specific "metabolites" from various drug molecules to reveal the presence of a drug in the person's system. These metabolites, essentially drug residue, are identifiable after the drug has entered the bloodstream and passed through the body. From the bloodstream, the drug molecules end up in the hair. Depending on hair growth, these residual drug indicators can be present for at least 90 days after the last actual drug use occurred.

How Is the Test Conducted?

• Hair used for a hair follicle drug test generally needs to be about 1.5 inches in length, in order to test for the uniform period of around three months of activity. Somewhere between 50 and 70 strands of hair are generally used, in order to factor in different hair pigments when analyzing the results. If taking such a large hair sample from the head is not possible due to near baldness, there are a few other areas on the body from which hair can be collected. Pubic hair may never be used. If no hair is available anywhere, another test, such as a urine test, may be substituted.

What Drugs Can Be Detected?

• Hair follicle tests can detect most illegal drugs in wide distribution. They focus on five categories of drugs, some of which include more than one substance. The categories are marijuana, cocaine (which includes Benzoylecgonine), methamphetamine (which includes ecstasy), opiates (including morphine and codeine) and phencyclidine or PCP. Each drug has unique molecules that are discovered in testing to identify someone as a user of a specific drug.

What's the Difference Between Tests?

• Of the three major drug tests, hair follicle tests demonstrate the longest history of a person's behavior. The urine test is designed for short-term testing, usually reflective of the last several days of someone's activity. Finally, a saliva drug test provides the shortest time span for testing and is typically used to determine if someone is high in the moment rather than to assess pass behaviors.

Counter-Testing Industry

• There are certain companies selling products that promise to detoxify your hair for an upcoming drug test. One of these companies, a website called ipassedmydrugtest.com advertises specially formulated shampoos designed to expel toxins from the hair, supposedly allowing for a clean hair follicle drug test. Prices for such products are pretty steep, ranging from anywhere from $50 to $130 and more in some instances.