A hair follicle drug test analyzes a small hair sample to detect past drug use. Often used for pre-employment screening and legal purposes, it offers a longer detection window than other drug tests. This article details what a standard 5-panel hair follicle test screens for, how it works, and its detection capabilities.
The Five Drug Categories
A standard 5-panel hair follicle test screens for five main classes of illicit substances and commonly misused prescription drugs. These categories include Amphetamines, which encompass substances like methamphetamine, MDMA (ecstasy), and MDEA. Another category is Cocaine, including crack cocaine.
Opiates form a significant group, with the test detecting substances such as codeine, morphine, and heroin. The test also screens for Phencyclidine (PCP), often known as Angel Dust. Finally, Marijuana is detected through its primary metabolite, THC.
How Hair Follicle Testing Works
Hair follicle testing involves collecting a small hair sample, typically from the crown of the head, close to the scalp. About 90 to 120 strands of hair are usually needed, with a length of approximately 1.5 inches. This collection process is non-invasive and is often performed under supervision to prevent tampering.
Once collected, the hair sample is sent to a laboratory for analysis. Drugs and their metabolites, which are breakdown products of drugs in the body, enter the bloodstream after consumption. These substances then become incorporated into the hair shaft as it grows from the follicle. The laboratory analyzes these incorporated drug metabolites, providing a historical record of drug use. Initial screening tests are performed, and any presumptive positive results undergo confirmatory testing to ensure accuracy.
Detection Window and Test Considerations
A hair follicle test typically provides a detection window of up to 90 days for drug use. This timeframe is based on the average growth rate of head hair, which is about half an inch per month. Therefore, a 1.5-inch hair sample reflects approximately three months of a person’s drug history.
It is important to note that hair tests cannot detect very recent drug use, as it takes about 7 to 10 days for drug metabolites to grow into the hair shaft and become detectable above the scalp. If an individual has very short head hair or is bald, body hair can be used as an alternative sample. While body hair can provide a longer detection window, its growth rate is less consistent than head hair, making it harder to pinpoint specific timeframes of use.