Hydroxyzine is a prescription medication, often recognized by its brand names Vistaril or Atarax, and is classified as a first-generation antihistamine. This medication is commonly prescribed for treating allergic reactions, reducing anxiety, and providing sedation due to its effects on the central nervous system. When considering a drug test, many individuals wonder if a legally prescribed medication like hydroxyzine could lead to a positive result. Understanding the components of standard drug screens and the body’s process for breaking down the drug is necessary to answer this question.
Standard Drug Panels and Hydroxyzine Detection
Standard drug testing panels, such as the common 5-panel or 10-panel screens used for pre-employment or probation, are designed specifically to detect illicit substances and commonly abused prescription drugs. A 5-panel screen typically targets five drug classes: marijuana (THC), cocaine, opiates, amphetamines, and phencyclidine (PCP). The more comprehensive 10-panel tests expand this list to include substances like benzodiazepines, barbiturates, and sometimes methadone. Hydroxyzine is generally not included on the target list for these routine drug panels because it is not classified as a controlled substance and is not a drug of abuse that is typically screened for. These initial screening tests use immunoassay technology designed to identify specific chemical structures or their metabolites, making it unlikely to cause a positive result for the drug itself.
Metabolites and Potential False Positives
Although hydroxyzine is not directly screened for, a positive test result can occur due to a phenomenon called cross-reactivity during the initial immunoassay screen. When the body processes hydroxyzine, it is metabolized into several compounds, the most significant of which is cetirizine, the active ingredient in the common over-the-counter allergy medication Zyrtec. The chemical structure of hydroxyzine, or its metabolites, is similar enough to certain other drug classes that it may confuse the antibodies used in the immunoassay screening test. This lack of specificity in the initial screen can sometimes result in a false positive, where the test mistakenly identifies the hydroxyzine compound as a different substance. Hydroxyzine has been reported to cause false positives for tricyclic antidepressants and, less commonly, benzodiazepines.
Verification and Confirmation Testing
If an initial immunoassay screening test returns a preliminary positive result, it is not considered definitive and must be followed by a mandatory confirmation test. This next step uses highly accurate laboratory techniques, specifically Gas Chromatography/Mass Spectrometry (GC/MS) or Liquid Chromatography/Mass Spectrometry (LC/MS/MS). These advanced methods are considered the gold standard in forensic toxicology because they precisely separate and identify the unique molecular structure of every compound present, including hydroxyzine and its metabolite, cetirizine. Confirmation tests are highly specific and can definitively distinguish between a legally prescribed medication and an illicit drug, correcting any false positive that occurred in the initial screen. Individuals who receive a preliminary positive result must provide documentation, such as a prescription or doctor’s note, to the Medical Review Officer (MRO), who verifies the prescription and reports the final result as negative.