A Saliva Drug Test is an efficient way to tell if someone has used illegal substances within the last week or so. This test is used in many different facilities for testing. Some employers use this form of testing during the interview process and when someone is expected of drug use after employment. This test is shown to be the best type of drug test; however there are some that debate this issue. Some of the main substances that this test searches for are traces of: marijuana, cocaine, and opiates. This test is used more than any other drug test currently.