Some causes of false-positive drug test results include lab errors, diet pills, sleeping pills and over-the-counter drugs, such as cold medicines, ibuprofen, hay fever medications and nasal decongestants, reports CVS Pharmacy. Significant consumption of poppy seeds, such as eating a pastry containing lots of poppy seeds, is also a possible cause of false positives. Another potential cause is intake of hemp food products, such as hemp oil.
Diabetes, kidney disease, liver disease, amoxicillin and cocaine-derived topical anesthetics can lead to a false-positive drug test result for cocaine, notes Columbia University. Using an at-home drug test kit also increases the chance of false positives due to user errors.
It's important to have a qualified testing center perform a secondary drug test to determine the cause of the false positive from the initial result, suggests Columbia University. If individuals who received false-positive results are currently taking prescription medications, they should ask their doctors if the medicines can affect drug test results.
Typical substances that companies and schools test people for include methamphetamine, anabolic steroids, cocaine, heroin and marijuana, states CVS Pharmacy. Some companies also test employees for alcohol, prescription-type stimulants, phencyclidine or hallucinogenic drugs. A common, accurate type of drug test is urine testing, which involves an immunoassay test to identify the concentration of a particular drug. It also involves gas or liquid chromatography to confirm the initial test's results.