Certain over-the-counter (OTC) medications can surprisingly lead to false positive results for benzodiazepines on standard drug screenings. These instances typically arise due to the cross-reactivity of common medications with the chemicals used in initial drug tests.
Understanding False Positives in Drug Screenings
Drug screening tests, particularly initial immunoassay screenings, are designed to be highly sensitive to detect the presence of various substances quickly. However, this high sensitivity can sometimes lead to false positive results because other compounds with similar chemical structures can trigger a positive reading. This phenomenon is known as cross-reactivity.
It's crucial to understand that an initial positive screening result does not definitively confirm the presence of benzodiazepines. Confirmatory tests, such as gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS), are far more specific and accurate. These advanced tests can precisely identify the chemical compounds present, distinguishing between actual benzodiazepines and other substances that may have caused an initial false positive.
Over-the-Counter Medications Linked to False Positive Benzodiazepine Tests
From the various medications known to produce false positive results for benzodiazepines, two commonly available over-the-counter drugs are noteworthy:
| Over-the-Counter Medication | Primary Use |
|---|---|
| Aspirin | Pain relief, fever reduction, anti-inflammatory |
| Dexbrompheniramine | Antihistamine, commonly found in cold/allergy remedies |
Key Over-the-Counter Culprits
- Aspirin (Acetylsalicylic Acid): A widely used non-steroidal anti-inflammatory drug (NSAID) for pain relief, fever reduction, and anti-inflammatory purposes. Its chemical structure can sometimes interfere with benzodiazepine immunoassay tests.
- Dexbrompheniramine: An antihistamine often included in multi-symptom cold, flu, and allergy medications available without a prescription. Similar to aspirin, its presence can lead to a false positive for benzodiazepines on an initial screen.
Other Medications That Can Cause False Positives
Beyond OTC drugs, many prescription medications have also been confirmed to produce false positive results for benzodiazepines on drug tests. While these are not over-the-counter, it's important to be aware of them for a comprehensive understanding of potential interferences:
- Antidepressants: Sertraline, Desipramine
- NSAIDs: Oxaprozin
- Antihistamines: Cyproheptadine
- Muscle Relaxants: Chlorzoxazone
- Diuretics: Chlorothiazide
- Antispasmodics: Dicyclomine
- Antiparkinsonian Agents: Benztropine mesylate
- Antibiotics: Cloxacillin
- Alpha-agonists: Clonidine
- Appetite Suppressants: Diethylpropion
What to Do If You Get a False Positive Result
If you take any medication, whether prescription or over-the-counter, and receive a positive benzodiazepine result on a drug screening, it's important to take the following steps:
- Disclose All Medications: Always provide a complete list of all medications, supplements, and even herbal remedies you are taking to the testing facility or employer/physician before or immediately after the test. This information is crucial for interpreting results accurately.
- Request a Confirmatory Test: If an initial immunoassay screening returns a positive result for benzodiazepines and you are certain you have not taken them, insist on a confirmatory test. Methods like GC-MS or LC-MS are highly reliable and can differentiate between actual benzodiazepines and other substances causing a false positive.
- Consult Your Healthcare Provider: Discuss the results with your doctor. They can provide documentation of your prescriptions and help explain how your medications might have influenced the test outcome.
Understanding that common medications, including some over-the-counter options like aspirin and dexbrompheniramine, can lead to false positive drug test results is vital for accurate interpretation and peace of mind.
