If you're like most people, you probably don't think about the potential consequences of taking over-the-counter (OTC) drugs. You pop a few pills to get rid of a headache or help you sleep and go about your day. Unbeknownst to many, some of these OTC medications can affect common drug tests.
One OTC drug, in particular, Nyquil, has been known to cause false-positive results and make people fail their routine drug screenings. But how exactly can Nyquil cause you to fail your drug test?
What is a False-Positive Drug Test Result?
A false-positive means that the drug test detected drugs in your system even though you didn't take any. So, if you've taken an OTC medicine and then failed a drug test, it's likely that the ingredients in the medication you've taken are to blame.
Some of the most common drug tests include:
These tests can screen for a wide variety of drugs, including:
- Alcohol
- Amphetamines
- Marijuana
- Opioids
How Can Nyquil Make You Fail a Drug Test?
One of the most common ingredients present in drugs that can cause a false-positive is dextromethorphan or DXM. DXM is an active ingredient responsible for making you drowsy and is found in many cough suppressants, like Nyquil, Robitussin, and Vicks 44. When taken in high doses, DXM can cause hallucinations and out-of-body experiences. It's generally considered safe when DXM is taken at lower doses like those found in over-the-counter medications.
However, even at lower doses, DXM can still cause a false-positive for opiates like PCP. This is because DXM can sometimes be metabolized into PCP in the body. So, if you've taken Nyquil or another OTC medication containing DXM, it's possible that when you take a urine drug test, it may come back positive for PCP.
Another ingredient in Nyquil that can cause a false-positive is doxylamine. Doxylamine is an antihistamine found in many OTC cold and flu medicines. An excessive amount of doxylamine can cause a false-positive on a drug test for methadone. Methadone is a synthetic opioid used to treat pain and addiction.
While doxylamine is not an opioid, it shares a similar chemical structure to methadone. This similarity can sometimes cause the test to appear positive for methadone.
Other Common Drugs that Can Cause a False-Positive
Apart from Nyquil, there are also ingredients found in other common drugs that can cause a false-positive. These include:
- Antidepressants: Tricyclic antidepressants like amitriptyline can cause a false-positive on a drug test for LSD.
- Painkillers: Ibuprofen and naproxen can cause a false-positive for THC.
- Cold medicines: Some cold medicines can cause a false-positive for amphetamines.
- Diabetes medications: The diabetes medication metformin can also cause a false-positive for amphetamines.
The active ingredients in these drugs can still periodically be metabolized into other substances in the body and can cause false-positives on urine drug tests.
It's important to remember that if you've taken any of these drugs and are worried about failing your drug test, it's best to speak to your employer, doctor, or the person administering the test. They'll be able to advise you on what to do and whether you need to take any special precautions. You can also speak to the medical review officer (MRO) after your test results come back.
And speaking of an MRO...
What to Do if You Incorrectly Fail a Drug Test
If you've taken an OTC medication and then find out that your drug test results come back positive, you'll most likely want to speak directly with the MRO.
An MRO is a licensed physician who is responsible for reviewing and interpreting drug test results. They will also take into account any medications that you're taking that could cause a false-positive. The MRO can contact your prescribing physician to confirm that the medication you're taking could cause a false-positive.
Preventing False-Positive Results
Failing drug tests can have serious consequences, especially if you're subject to workplace drug testing. While it's easy to advise that you stop taking OTC medications for a while until the ingredients clear your system, this isn't always possible or practical for everyone.
If you can't avoid taking these medications, you can do a few things to try and prevent a false-positive result. These include:
- Read the labels: Make sure to read the labels on any OTC medications you take. Check for any warnings about drug interactions or possible false-positive results.
- Check with your doctor or pharmacist about any concerns you might have: If you're taking prescription medications, communicate with your doctor to see whether or not the medications you're taking are likely to cause a false-positive.
- Keep track of your medications: Be sure to keep track of the medications you're taking, both prescription and OTC. This will help you remember which ones could cause a false-positive result.
- Talk to your employer: If you're subject to workplace drug testing, be sure to talk to your employer about any medications you're taking. They may be able to provide you with a list of drugs that could cause a false-positive.
Taking these steps will help you avoid any potential problems with false-positive drug test results.
The Bottom Line
OTC medications, like Nyquil, can sometimes cause a false-positive result in drug tests. While false positives are relatively rare, they can still happen. So, it's always best to be prepared and take the necessary steps to avoid any potential problems. If you're ever in doubt about whether a medication you're taking could cause a false-positive, be sure to read the labels and talk to your doctor or employer about any concerns you might have.
If you need reliable drug testing, contact US Drug Test Centers, locate a testing center near you, or order a test online.
Ashlee Arnold is one of the founders of US Drug Test Centers and is currently the Vice President. 
