Saliva is a refined version of plasma, that has the capability to contain trace amounts of drugs and their ensuing metabolites for a period of 24-36 hours. This forms the basis of saliva drug test. It is also known as oral fluid drug test.

The saliva drug test kits comes in many forms and shapes. The general way of using such a kit is to place it in the mouth of the individual being tested. The kit draws the saliva through a membrane. The membrane allows saliva to wet the strips containing media of antigen dyes. The antigen dyes act as an indicator. Formation of color on the strip suggests a positive result. There is a particular color for each drug in question.

Saliva drug test can detect the following drugs. The detection time for each drug is given against them:

Alcohol – from time of intake to 12 hours.
PCP – from a few minutes after ingestion to the next three days.
Methamphetamine and ecstasy – half an hour from ingestion up to 3 days.
Amphetamines – a few minutes to 3 days of consumption.
Barbiturates – less than an hour after ingestion up to 3 days.
Opiates – from an hour after intake to 3 days.
Cocaine – a few minutes after ingestion up to one day.
Benzodiazepines – not yet known
Cannabis – a few minutes after ingestion up to one day.

Purpose
Saliva tests are used primarily for employment drug screenings. Federal mandates require screening for each of the drugs detected by the saliva testing prior to employment. The convenience and quick results make saliva testing an attractive choice for employers.

Benefits
Saliva tests can be performed in any location and do not require a professional nurse or lab technician to conduct the test or read the results. In addition, the results appear very quickly and can be read within five minutes. They are a low-cost, and non-invasive alternative to sending potential employees to a lab for drug testing and also are virtually impossible to trick.

Considerations
Traces of the drugs will only show in the saliva for 10 to 24 hrs after use. For this reason, a long-term drug user who stays clean for a few days before testing will appear to be completely drug free. In addition, while it is very difficult to trick a saliva test, it is possible to mask the traces of drugs by smoking cigarettes or eating certain foods.

Comparisons
Hair follicle testing shows the history of a person’s drug use, but the testing is not virtually instantaneous as with the saliva testing. Urine testing is more easily faked than a saliva test, but traces of drugs show in a urine test for a longer period of time than in a saliva test. Blood tests are extremely accurate and extremely difficult to fake, but are invasive and test results are slow.