There are instant test kits on the market. These are similar to home pregnancy tests and require the employer to manipulate a urine sample. Although these tests are considered accurate for immediate screening, they are useless in the event of a positive result, since that requires laboratory confirmation and retention of a sample for retesting by the subject. In addition, they are not that much less expensive then laboratory tests. Some employers use a ten-panel test, which includes prescription drugs that are legal to possess and use.
Employers can also test for blood alcohol.
Although each drug and person is different, most drugs will stay in the system for 2-4 days. For chronic users of certain drugs, such a marijuana or PCP, results can be detected for up to 14 days, and sometimes much longer. Sedatives, such as Valium, may stay in the system for up to 30 days. When the more expensive hair testing method is used, drugs can be detected for a 90-day period. Most employers will insist that a job applicant give the urine sample within a specific period of time, so that a drug user does not wait until the drugs leave the system.