Drug tests for benzodiazepines can yield positive results for various reasons, ranging from legitimate prescribed use to interactions with other medications.
Prescribed Benzodiazepines
The most direct cause of a positive benzodiazepine drug test is the legitimate use of a medication prescribed by a healthcare provider. Benzodiazepines are a class of central nervous system depressants that slow brain activity. They are commonly prescribed for conditions such as anxiety disorders, panic disorder, insomnia, and seizures.
Common examples of prescribed benzodiazepines include alprazolam (Xanax), diazepam (Valium), lorazepam (Ativan), and clonazepam (Klonopin).
Non-Benzodiazepine Medications Causing False Positives
Sometimes, a drug test may indicate the presence of benzodiazepines even when an individual has not taken them. This can happen due to certain non-benzodiazepine medications that cause a positive result on initial drug screening tests. This phenomenon is known as cross-reactivity, where the chemical structures of these other drugs are similar enough to benzodiazepines to trigger a positive reading.
Initial screening tests, often immunoassay-based, use antibodies to detect substances. These antibodies may mistakenly bind to compounds from other medications that share structural similarities with benzodiazepines, leading to a false positive. For instance, the antidepressant sertraline (Zoloft) has been reported to cause false-positive benzodiazepine results on immunoassay screens. Similarly, oxaprozin (Daypro), a non-steroidal anti-inflammatory drug (NSAID), can also lead to such results.
Efavirenz (Sustiva), an antiretroviral drug used in HIV treatment, may also cause a false positive. Over-the-counter medications like diphenhydramine (Benadryl) and doxylamine, found in some sleep aids, have also been linked to false-positive benzodiazepine screenings. High doses of NSAIDs like ibuprofen and naproxen may also contribute to these unexpected results. These instances highlight a limitation of initial screening tests rather than an error in the laboratory process itself.
Understanding and Confirming Test Results
Drug testing typically involves two main stages: an initial screening test and, if necessary, a confirmatory test. The initial screening, often an immunoassay, is a rapid and cost-effective method used for preliminary detection. However, these initial screens are known for their potential for false-positive results due to the cross-reactivity with other substances.
If an initial screening test yields a positive result, especially an unexpected one, a confirmatory test is usually performed. Gas Chromatography-Mass Spectrometry (GC-MS) or Liquid Chromatography-Mass Spectrometry (LC-MS/MS) are considered highly accurate confirmatory methods. These advanced techniques separate and precisely identify specific compounds, distinguishing actual benzodiazepines from other substances that might have caused a false positive on the initial screen.
If an unexpected positive result occurs, it is helpful to communicate openly with the testing facility or employer. Providing a detailed list of all prescription and over-the-counter medications, as well as any supplements recently used, is important. Requesting a confirmatory test, particularly GC-MS, can help ensure an accurate and definitive result, preventing potential misunderstandings arising from initial screening limitations.