The majority of drug testing is done by sending an applicant to a collection site, where a urine sample is obtained and sent to a certified laboratory for analysis. Negative results are normally available within 24 hours. Some employers use instant test kits that are similar in operation to a home pregnancy test. New testing methods, such as hair testing and saliva testing are also being used. Some employers use a 10-panel test, which includes prescription drugs that are legal to possess and use.
Employers can also test for blood alcohol levels.
Although each drug and each person is different, most drugs will stay in the system about two to four days. For chronic users of certain drugs, such as 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. Most employers will require an applicant to give the urine sample within a specific period of time, so that a drug user does not wait until the drugs leave the system. Laboratories and collection sites also have methods to determine if the applicant has attempted to alter the test sample by drinking excessive water, contaminating the sample, or by using some sort of product that is sold in the hope it will mask drug use.