How do at-home drug tests work?

At-home drug tests are over-the-counter (OTC) products that are designed to indicate if one or more specific drugs or illegal substances are present in the body by testing hair and bodily fluid samples. The reasons behind a purchase of an at-home drug test vary from case to case, but their immediate use includes diagnosis. These testing methods range from the very basic to more advanced variants that can track both prescription and illegal substances. The three most common at- home drug tests will detect the presence of these substances in an individual's saliva, urine and hair follicles. Generally, urine/saliva tests are the products that can detect the widest range of potential drugs in the shortest amount of time, while hair follicle tests must be sent to a laboratory to obtain full results. What do at-home drug tests check for?

At-home drug tests are used by government agencies, businesses, doctors and families to assess whether an individual has recently taken an illegal substance or drugs of abuse that are prescription medicines taken for non- medical purposes. These tests indicate the presence of drugs including oxycodone, ecstasy, marijuana, cocaine, barbiturates, methadone, methamphetamine, PCP, benzodiazepine, opiates, tricylic antidepressants and more (U.S. Food and Drug Administration).