There are five primary types of drug tests: urine, , hair, saliva, and drug residue detection. 
Urine Screen Drug Tests
•    Inexpensive and reliable drug screening test method
•    Can be done at home, office or school, non-negative results must to be confirmed
•    Detect drugs use primarily within the past week (some of the drugs even less). 
•    Can be adulterated, but it is exist specimen validity tests to prevent it. 
Saliva (Oral) Drug Testing
•    Are a little more expensive than urine testing, but less than hair follicle
•    Are considered a relatively non-intrusive method of drug testing. 
•    Are easy to administer but require lab processing to confirm positive result. 
•    Detect use primarily within the past few days, but cheating protected
•    Can detect more recent use than other testing methods. 
Hair Follicle Laboratory Test
•    Are considered a relatively non-intrusive method of drug testing. 
•    Detect substance use over a longer period (up to 90 days), but usually not detect use within the past week. 
•    Require a sample of hair about the diameter of a pencil and 1.5 inches long. They can not be done with a single hair. 
•    Claims to be able to reliably protected from the adulteration 
Drugs Residue Tests
•    Are considered an absolutely non-intrusive method of drug testing 
•    In most cases can not prove the person who used drugs 
•    100% accurate and very sensitive, could be applied to determine the nature of unknown substances
•    Very inexpensive and perfect for preliminary testing