Some of these at-home drug tests are also designed to detect multiple substances from a single sample through a two-step process. The first step is the actual at-home sample collection and the ...

Hair follicle drug tests involve removing a small hair sample for laboratory testing. Results can show if a person has been using certain drugs or prescription medications in the previous 3 months.

For example, United States federal law mandates that people working in the transportation industry take regular drug tests. Laws about employee drug testing differ geographically. A person should ...