Cold medicines and drug test results

Woman with the flu taking medicine

Health experts say that this year is on track to be “one of the worse flu season in decades.” The CDC reported 6.4 million flu illnesses and 55,000 hospitalizations in the U.S. as of January 2020.

Some common prescription and over-the-counter (OTC) medications may contain drugs such as codeine, hydrocodone, and sympathomimetics, which have been reported to affect workplace drug tests.


Codeine is used in some medications as a cough suppressant. When codeine enters the body and is metabolized, it changes to morphine. Both codeine and morphine are used to relieve pain. The use of codeine-containing products may result in a positive drug screen for codeine and/or morphine.


This narcotic is widely used to treat pain and is also FDA-approved for use in a handful of prescription medications as a cough suppressant. It is also an extremely popular drug of abuse as it can produce feelings of euphoria. Unfortunately, it is highly addictive, and when improperly used, hydrocodone can lead to serious illness or injury. Donors using medications that contain hydrocodone may test positive in some drug test panels.


Drugs such as pseudoephedrine, ephedrine, and phenylephrine are commonly used as decongestants in OTC cold and flu medicines or as appetite suppressants. Sympathomimetics like those listed above will not produce a confirmed, positive drug screen. It is a common misconception that OTC cold medications may produce positive results in workplace drug tests but the fact is that while some of these may cause a specimen to initially screen as non-negative, they will not confirm positive in the second step of the GC/MS testing process. With the two-tiered testing process and the definitive identification and quantification with GC/MS confirmation, the use of these OTC drugs will not result in a confirmed positive drug test.

Keep a list of medications

It is important that the donor keep a record of any such medications that may affect a drug screen. It is suggested that the donor write a list of these medications on his/her copy of the custody and control form after providing a specimen for a drug screen. This list may serve as a useful reminder to the donor should a justification be required. When a positive result is sent to the Medical Review Officer (MRO), information relating to valid prescriptions or medication use will assist the donor when contacted by the MRO during his/her review and verification of the positive result.

Get started by referencing our Guide to Establishing a Workplace Drug Testing Program.

At Quest Diagnostics, we understand that it is our responsibility to aid you in making informed drug screening decisions. When complex issues like these arise, we are always willing to assist you to ensure that your donor’s results are accurate.

Sign up for our monthly newsletter to get the most up-to-date drug testing information.

For more information about drug testing, visit our website or connect with us online.

Photo courtesy of MarketWatch


First published in November 2010 and updated February 2020