Why Urine Drug Testing?

Urine is the most common sample type used for drug testing by employers and detects recent drug us. It is the only testing method approved for federally-mandated testing. A urinalysis will show the presence of a drug in the system after the drug effects have worn off; however, the length of time varies by drug.


How long do drugs stay in your system?

Many variables may affect the amount of time that a drug remains detectable in the urine or other biological samples, including:

  • a drug’s half-life
  • subject’s state of hydration and fluid balance
  • frequency of drug use
  • route of administration
  • cut-off concentration used by the testing lab to detect the drug.

General guidelines are available for detection times. Many drugs stay in the system from 2 to 4 days, although chronic use of marijuana can stay in the system for 3 to 4 weeks or even longer after the last use.


How long does it take to get drug test results?

Results from workplace drug testing are fairly quick and can usually be received in a few days. An employer may also request to have the test done with a rapid test that can provide results on the same day. Negative results are usually received within 24 hours; however, a positive screen will require further testing that may take a few days up to one week.


Can a drug test be false positive or false negative?

A concern for anyone undergoing drug testing is the possibility of a false positive result. Initial screening drugs tests may infrequently result in false positive results, although confirmatory (GC-MS) testing greatly lessens the chances of a false positive – reducing the risk to close to zero.

It is important that a person undergoing drug testing complete an accurate history of all prescription, OTC, and herbal drug use prior to the time of the sample collection. Certain substances, over-the-counter (OTC) or prescription drugs may result in false positives due to cross-reactivity with other substances, although many assays have been reformulated to avoid these possibilities.