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Do cold and flu tablets show on a drug test?

5 min read

According to research from Boston Medical Center, drug tests can produce false positives in 5% to 10% of cases. This statistic is particularly relevant for individuals taking common cold and flu tablets, as some ingredients can sometimes interfere with initial drug screenings, leading to an incorrect result.

Quick Summary

Certain over-the-counter cold and flu medications containing ingredients like pseudoephedrine, diphenhydramine, and dextromethorphan can trigger a false positive on initial drug tests. However, definitive laboratory confirmation testing, such as Gas Chromatography/Mass Spectrometry (GC/MS), can accurately distinguish between these legal compounds and illicit substances.

Key Points

  • False Positives on Initial Screens: Many OTC cold and flu ingredients, including pseudoephedrine, diphenhydramine, and dextromethorphan, can cause a false positive result on initial immunoassay drug tests due to similar chemical structures.

  • Confirmatory Testing Provides Accuracy: A more specific test, like Gas Chromatography/Mass Spectrometry (GC/MS), can accurately differentiate between legal cold medicine ingredients and illicit drugs, overturning a presumptive false positive.

  • Not All Cold Medicines are Created Equal: Some prescription cold and flu medications contain actual controlled substances like codeine or hydrocodone, which will produce a true positive result for opioids.

  • Disclosure is Key: It is crucial to inform the testing facility about any over-the-counter or prescription medications you are taking before your test to avoid confusion.

  • Request Confirmation if Necessary: If an initial screening test comes back positive, you have the right to request a confirmatory test to prove that a legal medication, not an illegal substance, caused the result.

  • Document Your Medications: Keep a record of your medication use, including prescriptions or packaging from OTC tablets, as supporting evidence in case of a false positive.

In This Article

A common cold or flu can hit at the worst possible time—especially if a drug test for employment or probation is on the horizon. Many people wonder, "Do cold and flu tablets show on a drug test?" The answer is complex. While most legal, over-the-counter (OTC) medications will not cause you to fail a definitive drug test, they can cause a presumptive or false positive on the initial screening. This is a crucial distinction to understand, as the testing process involves different stages with varying levels of accuracy.

Understanding How Drug Tests Work

Drug screening typically involves a two-tiered testing process. The first step is an initial immunoassay (IA) screen. This test is fast, inexpensive, and designed to screen for a broad category of substances. It uses antibodies to detect drug classes, but its main drawback is a tendency to sometimes produce false positives because it can cross-react with other compounds that have similar chemical structures.

The second step, confirmatory testing, is performed if the initial immunoassay screen is non-negative. This is a much more specific and sophisticated test, most commonly Gas Chromatography/Mass Spectrometry (GC/MS). The GC/MS test acts as a 'chemical fingerprint,' separating and identifying individual compounds within the sample. This allows labs to distinguish between legal medications and illicit drugs, correcting any false positives from the initial screening.

Cold and Flu Ingredients That Can Trigger a False Positive

Several ingredients found in common OTC cold and flu tablets can cause a preliminary false positive during the initial immunoassay test. The most common examples include:

Pseudoephedrine and Ephedrine

  • Found in: Decongestants like Sudafed (pseudoephedrine) and some combination cold and flu products.
  • Potential False Positive for: Amphetamines and methamphetamines. These ingredients are chemically similar to amphetamines, which can confuse the initial screening test. However, a GC/MS confirmation test can reliably differentiate between them.

Diphenhydramine

  • Found in: Antihistamines like Benadryl and nighttime cold and flu remedies (e.g., NyQuil).
  • Potential False Positive for: Methadone, certain opioids, or PCP. While it's not a direct match, the initial test can sometimes mistake the chemical structure for these substances. Confirmatory testing is needed to clear the result.

Dextromethorphan (DM)

  • Found in: Cough suppressants like Robitussin DM and Delsym.
  • Potential False Positive for: Opiates or PCP. Similar to other ingredients, the initial screening's antibody test can cross-react with Dextromethorphan metabolites. Definitive GC/MS testing can clarify the result.

Doxylamine

  • Found in: Sleep aids like Unisom and some nighttime cold formulas.
  • Potential False Positive for: Methadone and PCP, particularly at high or toxic doses. Overdose or abuse of doxylamine, though rare, is a known cause of false positives on immunoassay tests for these drugs.

Codeine and Hydrocodone

  • Found in: Prescription-strength cough suppressants. These are narcotic opioids.
  • Result: Unlike the other ingredients mentioned, these will result in a true positive for opioids. It is important to disclose any prescriptions containing these substances to the testing facility beforehand.

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs)

  • Found in: Pain relievers like ibuprofen (Advil) and naproxen (Aleve), which are common in cold and flu products.
  • Potential False Positive for: In rare instances, ibuprofen can cause false positives for cannabinoids (THC) or barbiturates, while naproxen can trigger a false positive for THC.

Comparison of Testing Methods

To illustrate the critical difference between initial and confirmatory testing, consider the following table:

Feature Initial Immunoassay (IA) Screen Confirmatory Gas Chromatography-Mass Spectrometry (GC/MS)
Purpose Rapid, cost-effective preliminary screening. Highly specific and accurate analysis for confirming initial results.
Principle Uses antibodies that bind to a class of drugs. Separates and identifies individual compounds based on their unique chemical 'fingerprint'.
Cross-Reactivity Prone to cross-reactivity with similar compounds, leading to false positives. Very low risk of cross-reactivity due to high specificity.
Accuracy Presumptive result, can be inaccurate due to interference. Definitive and accurate, considered the gold standard.
Resolution Will flag a sample for further testing if positive. Can differentiate between a legal medication and an illicit drug.

How to Handle a Drug Test While Taking Cold Medicine

If you are required to take a drug test while ill, the best course of action is to be proactive and transparent. Here are some steps you can take to prevent or address potential issues:

  • Disclose All Medications: Inform the testing facility or employer of all medications you are currently taking, including both prescription and OTC products. Providing this information upfront helps in the event of a flagged initial test.
  • Provide Documentation: For prescription medications containing substances like codeine, have proof of a valid prescription. For OTC products, retaining the packaging or a note from a doctor can serve as useful documentation.
  • Request Confirmatory Testing: If an initial screen comes back positive, immediately request a confirmatory test using a more accurate method like GC/MS. This is the most reliable way to clear your name, as the confirmation test will identify that the flagged substance is a legitimate cold medicine ingredient and not an illegal drug.
  • Choose Alternatives if Possible: If you have advance notice of a drug test and are concerned, consider alternative remedies for your cold. Some over-the-counter products are available without pseudoephedrine or dextromethorphan. For instance, phenylephrine is often used as an alternative decongestant in oral formulations, though an FDA panel has questioned its efficacy. Consult a healthcare professional or pharmacist for guidance on safe alternatives that won't interfere with testing.

Conclusion

While the prospect of a false positive on a drug test can be stressful, understanding the science behind the screening process can alleviate much of the anxiety. Legal, over-the-counter cold and flu tablets can indeed cause a preliminary false positive, but they will not result in a confirmed positive result when a more specific test is used. Being transparent with testing administrators and advocating for a confirmatory test if needed are the most effective strategies for ensuring an accurate and fair outcome. It is always wise to inform the testing facility of all medications you are taking to prevent misunderstandings and potential complications.

For more information on medications and false-positive drug tests, consult resources from Quest Diagnostics, an authoritative source on the topic.

Frequently Asked Questions

Sudafed, which contains pseudoephedrine, can cause a false positive result for amphetamines or methamphetamines on an initial drug screen. However, a confirmatory GC/MS test will be able to distinguish between pseudoephedrine and illicit drugs, confirming the legal substance.

Benadryl, which contains diphenhydramine, can sometimes cause a false positive for methadone, certain opioids, or PCP on an initial drug screen. A follow-up confirmatory test is typically required to resolve the issue.

Yes, many cough syrups contain dextromethorphan (DM), which can cause a false positive for opiates or PCP on an initial urine drug test. Some prescription cough syrups contain actual opioids like codeine, which will cause a true positive.

NyQuil contains a combination of ingredients, including doxylamine and dextromethorphan, both of which can cause false positives on initial drug screens for methadone, opiates, or PCP. Disclosing its use is recommended before testing.

To avoid a false positive, disclose all medications to the testing facility, keep documentation like prescriptions or packaging, and be prepared to request a confirmatory test if the initial screening is non-negative.

An initial screen is a quick and less specific test prone to cross-reactivity with cold medicine ingredients. A confirmatory test, like GC/MS, is highly accurate and can definitively identify the specific compounds, eliminating false positives caused by legal medications.

The detection window varies based on the specific ingredients, dosage, and testing method. However, potential interference from cold medicine ingredients is generally cleared by a confirmatory test, so the duration in your system isn't the main concern, but rather the initial cross-reactivity.

References

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Medical Disclaimer

This content is for informational purposes only and should not replace professional medical advice.