
A saliva drug test is easier for everyone as it is easy to collect and not easy to fake with another sample. The testing individual takes a cotton swab and runs it around in your mouth. Some have a cotton pad where the toothbrush bristles should be. They place the cotton pad between the gum and the lower jawline for about three minutes, and it will collect the saliva. After collecting the sample, they place it in a sterile container for testing.
The one problem with saliva is that drugs cannot be detected in it for a very long time. So you have that on your side if you are using illegal substances. They also cannot detect a history of drug abuse either. If your employers has any suspicions about you taking any kind of illegal substances, they can use this particular test to find out if you are.
They will look for personality changes, missed deadlines, really strange reasons as to why they were missed, money stolen, a change in behavior and performance, and sudden outbursts over really small things. Any of these is a reason to test you for illegal substance abuse. Your employer doesn't really need a reason just a suspicion. Some companies enforce unannounced drug testing for just that reason.