Comparison of Saliva, Blood and Urine Testing
Previously, drug testing was completed by taking a blood or urine sample, or in some cases, a saliva sample. Testing saliva for drugs is also completed in some instances. However, it is not as effective as detecting drug use compared to the other methods. Saliva testing is mainly used to detect if drug use happened when less than 48 hours.
The problem with the blood sample is that the presence of drug might be filtered out quickly without the presence of the drug being detected when the test is done. Testing for drugs within a blood sample is more invasive, thus requiring the person to actually go into a medical facility and have blood drawn.
However, with a urine sample, the presence of a drug or medication is found to be there for a longer time inside the urine, as compared to the blood sample. Since they have become so common within the United States, some people have found ways of getting around the urine tests such as using a good (clean) friend's urine. Thus there is a higher level of error associated with urine drug testing and they are only moderately accurate in detecting certain drugs and not the drugs most commonly used. Unless there are cells released in the urine, there is also no way to genetically match a person to a urine sample.
These are just some facts about hair follicle drug testing and how it is has become more popular than urine drug testing. The presence of the drug can be deposited and detected within the hair for up to three months. Thus, if the person has only recently stop taking the drug just to pass the drug test, it will still be detected by hair follicle testing.