Drug test hair is a hair sample collected and analyzed to detect drug use. It is often used as an alternative to blood or urine tests, and it can identify drug use over a longer period of time.
Hair testing is a reliable way to detect drug use. It is can be used to detect drug use that occurred up to 90 days prior to the test. This is because drugs are incorporated into the hair as it grows, and they can be detected in the hair shaft for months after drug use has stopped.