False Positives
Sometimes a drug test result can be the product of human error, or even contamination; this is called a drug test false positive result. There are also a number of uncontrolled or controlled substances which can cause a drug test false positive. There are a number of substances, listed below, which can cause you to receives a drug test false positive this is something to be taken very seriously, as a drug test false positive can have serious consequences. Drug testing false positives actually occur reasonably often, and can be the reason to send you to the unemployment office or on a revocation hearing of your parole or probation. According to National Laboratories, drug test false positive occur up to 30 percent of the time, and legal substances can cause a drug test false positive as much as 38 percent of the time.

Here are some things to avoid prior to a drug test:
Certain antibiotics such as Penicillin and Tetracycline are known to sometimes cause drug test false positive results for heroin and cocaine.
Cold remedies, diet pills, hay fever remedies and pain relievers:
In blind testing, decongestants and many diet aids resulted in drug test false positive results for amphetamine use in one third of all test samples given to 40 leading substance testing laboratories. There are more than 300 over-the-counter drugs that can cause false positives on the EMIT, and new drugs being introduced every day.
Dental/Medical treatments:
Cain-based products, especially Novocaine, have been known to cause false positives for cocaine. Some legal products actually contain small amounts of illegal chemicals. All urine tests, including GC/MS will indicate a positive result because the metabolites derived from the substance are identical to the metabolites of the illegal drug.
Ibuprofen is a common pain reliever that, even in low dosages, can cause a false THC positive on the EMIT. This has supposedly been corrected.
Poppy seeds:
Though an extremely concentrated amount of poppy seeds are needed to obtain a false positive for opiates on the EMIT, it is possible.
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