In order to be considered in accordance with the Substance Abuse and Mental Health Services Administration (SAMHSA) guidelines, a drug test must detect the possible use of five illicit drugs: amphetamines, marijuana, cocaine, opiates and phencyclidines. SAMSHA also provides guidelines for what determines a test to be positive. Because different drugs have different characteristics and detection windows, a variety of drug testing options are available, including urine, saliva, hair, blood and sweat tests.
Urine
Urine testing, although considered intrusive, is the most common form of drug testing available. It is the least expensive testing method, ranging from $7 to $50, depending on the test. Urine testing shows either the presence or absence of drug metabolites, which are residues from a drug that remain in the body for a certain period of time after the effects of the drug have worn off. A positive test does not indicate current drug impairment, but rather the use of the drug in the recent past, according to the Separated Parenting Access and Resource Center. The test results can be affected by abstaining from drug use for a certain period of time before the test, which affects the reliability of the urine test.
Saliva
Saliva testing is slightly less common and a bit more expensive than urine testing, ranging from $15 to $75 per test. Samples of saliva are collected by taking a swab of the inner cheek. Saliva tests can detect drug use within the previous few days, which is usually indicative of current use. These tests are more reliable for methamphetamine and opiate use than for THC or cannabinoids found in marijuana and hashish.
Hair
Hair testing is the least invasive drug testing method, although it is several times more expensive than urine testing, ranging from $100 to $150 per test. Hair tests are used to detect drug abuse over longer periods of time, approximately 90 days, and cannot be used to detect current impairment or substance abuse within a week prior to the test. In order to get a positive reading, a hair test requires several strands of hair approximately the diameter of a pencil and 1.5 inches in length. The results of the drug test will not be affected by brief pauses in drug use. Although considered a very reliable drug testing method, the hair test is not the best option for detecting cocaine use, as it cannot detect the time frame of abuse for this particular drug.
Blood
Blood testing is the most expensive, most intrusive and most accurate drug testing method available. However, it is also the least common method used due to its high cost. A blood drug test measures the actual amount of alcohol or drugs in the blood, although it is more accurate for alcohol detection. This type of drug test can determine if the tester is currently under the influence; however, there is a short detection window for blood tests as substances move quickly from the blood to the urine, according to the U.S. Department of Labor.
Sweat
Sweat tests require the tester to wear a patch with a gas-permeable membrane for extended periods of time. The presence or absence of drugs is detected through the sweat that is picked up by the patch. This method of drug testing is most commonly used for those who are on parole or probation to make sure that the person is in compliance with specific terms. Controversy surrounds the accuracy of sweat tests; some researchers claim that because of extended wear, contamination is highly probable and can cause a false reading.
