There are five primary types of drug tests: urine, blood, hair, saliva, and sweat. Most common is the urine test which has the benefit of being inexpensive and less intrusive than the blood test.

Urine Tests

* Are the least expensive of the test methods (~$7-$50 for home version).
* Are considered an intrusive method of testing.
* Can be done at home (for example by parents) though require lab verification for accurate results.
* Detect use primarily within the past week (longer with regular use).
* Can be affected by abstaining from use for a period of time before the test.
* Are often temperature tested to insure sample integrity.

Saliva Tests

* Are a little more expensive than urine testing, but less than hair or blood. (~$15-$75).
* Are considered a relatively unintrusive method of drug testing.
* Are becoming more common.
* Are easy to administer but require lab processing to ensure accuracy.
* Detect use primarily within the past few days.
* Can detect more recent use than other testing methods.
* Have no nationally accepted standards or cutoff concentrations for detection, making results greatly dependent on the specific product purchased. This could also make results less-reliable and/or acceptable for legal cases.
* More reliable for detection of Methamphetamine and Opiates, less reliable for THC or Cannabinoids (2004).

Hair Tests

* Are currently several times more expensive than urine tests (~$100-$150).
* Are considered a relatively unintrusive method of drug testing.
* Detect substance use over a longer period (see detection period).
* Do not usually 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.
* Test positive a little more than twice as often as a urine test. In a recent study, out of 1823 paired hair and urine samples, 57 urine samples tested positive for drugs of abuse; while 124 hair samples from the same group tested positive.
* Are not significantly affected by brief periods of abstinence from drugs.
* Can sometimes be used to determine when use occured and if it has been discontinued. Drugs, such as opiates (codeine, morphine, heroin) lay down on the hair shaft very tightly and are shown not to migrate along the shaft, thus, if a long segment of hair is available one can draw some “relative” conclusions about when the use occurred. However cocaine, although very easy to detect, is able to migrate along the shaft; making it very difficult to determine when the drug was used and for how long.
* Claims to be able to reliably differentiate between opiate and poppy seed use.
* We’ve heard that many hair tests now check for more than the SAMHSA-5, and include at least Cannabis, Ecstasy/MDMA, Cocaine, Opiates, Methamphetamine, Amphetamine, Phencyclidine (PCP), Benzodiazepines, & Barbiturates (2001).

Blood Tests

* Are the most expensive method of testing.
* Are considered the most intrusive method of testing.
* Are the most accurate method of testing.
* Are the least common method of testing (most likely due to cost).

Sweat (Patch) Tests

* Are considered a relatively intrusive method of drug testing because they require the wearing of a patch for an extended period of time.
* Are still relatively uncommon.
* Are controversial in terms of accuracy. There is some reason to believe that surface contamination (such as cannabis smoke) can cause a false reading.
* Can detect use which would not trigger other tests. Because of the short detection period for many drugs in urine, single use of many drugs longer than a week prior to using the patch will not cause a positive urine test. Because the skin patches are gathering sweat over an extended period of time, it is possible that any use during that time will produce a positive result.

TEST SENSITIVITY
The Substance Abuse and Mental Health Services Association (SAMHSA) provides guidelines for what qualifies as a positive drug test. If a test does not give results higher than the guidelines, it does not qualify as a “positive” test. If an immunoassay test gives positive results, a second Gas Chromatography test must also give positive results before a result of “positive” is announced. The following chart shows the guidelines by substance.

Initial Test Cutoff Concentration
SUBSTANCE Initial Test
(IMMUNOASSAY) Confirming Test
(GC / MS)
Cannabis 50 ng/ml 15 ng/ml
Cocaine 300 ng/ml 150 ng/ml
Opiates 2000 ng/ml 2000 ng/ml (morphine)
2000 (codeine)
6-Acetylmorphine)
Amphetamines 1000 ng/ml 500 ng/ml
PCP 25 ng/ml 25 ng/ml
Notes: Cannabis is detected through its metabolite Delta-9-tetrahydrocannabinol-9-carboxylic acid. Cocaine is detected by its metabolite Benzoylecgonine. Methamphetamine positive confirming test requires both 500ng/ml of methamphetamine and 200ng/ml of amphetamine.
from SAMHSA Feb 2005, 69 FR 19644

Some companies are getting around these guidelines by reporting the levels found without categorizing them as a “positive” or “negative” test. This seems to be a problem primarily with mail-in home tests rather than corporate testing.