A drug test can be done in several ways, based on where the specimen is taken from. Sources are from urine, blood, hair, sweat and saliva. They differ in cost, how long the drug will show and accuracy of test results. Saliva tests can show drug use within hours or up to a maximum of 2 days. For more info, visit www.drugtestingfacts.net/saliva-drug-test/ - Cached
A drug test will analyze some bodily specimen to see if a specific drug has been ingested. Drug tests can use urine, blood, hair, or saliva samples. Each of these specimens can detect drug use for a certain period of time. If you are wondering how far back does a saliva drug test go, the answer is it depends. Most drugs can be detected from the time of ingestion until 2 to 4 days later. . Marijuana can only be detected for 24 hours, in most cases. Saliva tests became popular because the are very hard to tamper with.