Levaquin Can Cause False-Positives For Opioids

It is important to let your doctor or drug tester know you are taking Levaquin.

Question

I am on a list for a liver transplant. I may not have alcohol or opiates. I am on a new antibiotic called levofloxacin. My recent blood work turned up trace amounts of both alcohol and opiates. could levofloxacin be creating a false positive?

Asked by frank frankie On Apr 15, 2019

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On Apr 16, 2019
Man Holding Urine Drug Cup With Text - Levaquin False-positive Drug tests

Overview

Levaquin (levofloxacin) is classified as a 'quinolone' antibiotic.

Multiple studies have shown that quinolone antibiotics, like Levaquin, can cause false positives on urine drug screenings for opioids and opiates.[1]

So, in your situation, having tested positive for an opioid despite not taking one, Levaquin could be the potential culprit that caused this reading.

If you have the opportunity, try to request to have a confirmatory test done. Urine drug tests are notorious for false-positive results. They should ideally only be used as an initial screening according to most studies on the matter because of this.[2]


Why Do False-Positives Happen?

False-positive results on urine drug screenings are relatively common unfortunately, simply based on how these tests work.

They utilize antibodies to bind and react to a particular drug substance. False-positive results occur when an antibody binds to the wrong drug substance, which typically occurs with drugs that have a similar molecular structure to the compound being tested for (but this isn't always the case).[3]

How often false-positives occur isn't specifically known, but since they are well documented, it is important to be aware of the possibility of them occurring.


Levaquin False-Positives

Quinolone antibiotics have been studied extensively for their role in potentially causing a false-positive result on urine drug tests. All of the following quinolones have published studies implicating them as being potentially responsible for erroneous test results:[4]

One study, based on their results, named Levaquin (levofloxacin) as one of the most likely quinolones to cause false-positive results for opiates:[5]

"Levofloxacin, oflaxacin, and perfloxacin were most likely to lead to a false-positive opiate result."

If you are taking Levaquin and are scheduled to get drug tested, it is extremely important to let your doctor and/or tester know.


What To Do?

If you are in the unfortunate position of receiving a false-positive test result from taking Levaquin, make sure you let your doctor or testers know about all of the documented evidence that exists regarding it.

Hopefully, they allow you to retest or allow you to use a confirmatory testing method.

As mentioned, urine drug screenings rely on antibodies to react with drug compounds. They don't actually definitively identify particular compounds in a sample. This is why the rate of false-positives is so high.

One commonly utilized confirmation test is known as gas chromatography-mass spectrometry (GC-MS).

GC-MS testing methods can accurately identify drug compounds in a sample and they do not rely on antibody reactions. They are often used to confirm or refute drug screening results.


Summary

Levaquin (levofloxacin), and quinolone antibiotics in general, have extensive documented evidence that they can cause false-positive results for opiates/opioids on urine drug screenings.

References
  1. ^ Urine drug screening: practical guide for clinicians. PubMed
  2. ^ Commonly prescribed medications and potential false-positive urine drug screens. PubMed
  3. ^ Toxicologic Testing for Opiates: Understanding False-Positive and False-Negative Test Results. PubMed
  4. ^ False-positive urine opiate screening associated with fluoroquinolone use. PubMed
  5. ^ Quinolones and false-positive urine screening for opiates by immunoassay technology. PubMed

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Dr. Brian Staiger is a licensed pharmacist in New York State and the founder of PharmacistAnswers.com. He graduated from the University At Buffalo with a Doctor of Pharmacy degree in 2010. He has been featured in numerous publications including the Huffington Post as well as a variety of health and pharmacy-related blogs. Please feel free to reach out to him directly if you have any inquiries or want to connect! He's answered thousands of medication and pharmacy-related questions and he's ready to answer yours! Brian.Staiger@PharmacistAnswers.com Office: 716-389-3076

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