Incredible How Long Can A Hair Drug Test Go References. Web while the average drug test detection time for hair spans several months, the test will not detect drug use within the last 7 to 10 days as there has to be enough hair growth to. Web most hair drug tests can detect heavy or regular use of certain illicit substances over the past three months.

Web what time period does a standard hair drug test cover? This detection window can show a pattern of drug use. Web a hair follicle drug test can determine patterns of illicit drug use or prescription medication misuse over a certain period — typically 3 months for hair samples that come from a.