4 Things that Can Elicit a False Positive Drug Test

A larger number of schools, hospitals and employers are now resorting to giving a drug test to employees to detect “drug of abuse” and ensure a drug free environment.
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There is a lot of potential fear and anxiety before a drug test. Some of the most common types of drug testing include pre-employment testing, post-accident testing, follow-up testing. One thing many people are worried about when deciding how to pass a drug test is what are the chances of a false positive drug test.

Urine drug screen (UDS) immunoassays such as iCup 3 Panel Urine Drug Test’ offer a quick and inexpensive method of detecting the presence of drug of abuse; however further confirmatory tests such as gas chromatography/mass spectrometry (GC-MS) may be required in some cases.

Even though urine tests return accurate result in most cases, the possibility of a false-positive cannot be ruled out completely. This means the test can show positive results even if the person did not use any illicit substance; though false positive happen rarely – approximately 1 – 2.5%.

Many cross-reactivity that exist with other analytes can also cause a false-positive result during the initial drug screen. According to Dwight Smith, MD of the VA Medical Center in Black Hills, S.D and his colleagues, false positive drug test results can be triggered due to the use of the antidepressant Wellbutrin, cold medications, and other such prescription drugs.

Moreover, HIV medication Sustiva can show marijuana use and quinolone antibiotic drugs can result in false positives for opioids, according to Smith. Thus knowledge of substance that can result in a false positive is necessary for both the person who conducts the test and the person undergoing the drug test.

4 Things that Elicit False Positive Drug Test

Whether you are looking forward to join a workforce or enroll in a higher education institution, institutions use drug tests to look for the following substances:

  • Amphetamines/methamphetamine
  • Cocaine
  • Marijuana/THC/Cannabinoids
  • Opiates/Heroin
  • Phencyclidine (PCP)

But one must be aware that the use of certain regular things can trigger false positive results and these include:

Cold Medications

Most cold medications alleviate the symptoms of sinus congestion and pressure by narrowing the blood vessels present on the nasal tract.

Pseudoephedrine, a synthetic amphetamine and the main component of most over-the-counter cold and flu remedies might help relieve the symptoms but it can also make you test positive for amphetamines. This was also confirmed at the 2010 American Psychiatric Association’s annual meeting.

Selegiline and Vicks Inhaler

Selegiline is mostly used to treat Parkinsons. Selegiline does not have anti-Parkinsons properties; so it must be administered along with levodopa/carbidopa.

But intake of Selegiline can result in positive test results for Amphetamine and Methamphetamine. So if you need to undergo a drug test while on Selegiline, you must bring it to notice.

Same is the case with Vicks Inhaler; it might ease breathing and provide relief from blocked nose caused due to cold and allergy; but it can make you test positive for Amphetamine and Methamphetamine.


Oxaprozin, also referred to as Oxaprozinum, is a non-steroidal anti-inflammatory drug (NSAID) that is used to relieve inflammation, joint pain, etc. Oxaprozin sold under the name Daypro, Dayrun or Duraprox lowers the levels of prostaglandins, a chemical that increases the level of pain and inflammation; thus providing relief.

Intake of Oxaprozin can result in positive test results for Benzodiazepine. It is also known to have a 100 percent false-positive rate.


Fluoroquinolone has become a popular class of antibiotics which is used to treat various infections. The newer drugs in this class such as Gemifloxacin, levofloxacin, and moxifloxacin have a broader spectrum of activity.

The risks associated with the older class drugs have also been lowered with the introduction of the new drugs; but there are high chances of testing positive for Opiate. In fact levofloxacin is most likely to lead to a false positive.


Common drugs that are used to relive or cure health conditions are known to trigger false positives, so people must be aware about the substances that can lead to false positives and make the people aware who are involved in the testing.

In case you test positive even if you haven’t been involved in drug abuse, you can use these information to protect yourself from the adverse effects of resulting positive in drug tests.

Nicky Gomez is a digital content manager at Test Country based out of the United States. She has recently started to write about drugs, drug testing, their impact on health and how people around are adversely affected. In her free time, she loves to cook for family, friends & paint. She strongly believes in giving back to the society as much as possible.

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