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Addiction and Substance Abuse

False positive cocaine urine test



I have been a health care professional for over 25 years. As I am in long-term recovery, I am often sent people who have tested positive for intoxicant use. Their employer requires that they listen to me for an hour while I inform them about the realities of intoxicant use and addiction.

Recently a young man tested positive for cocaine and swears that he has never used it.

I have surfed the net and find that a number of substances and conditions (amoxicillin, ampicillin, kidney disease, liver disease, tonic water) can produce a false positive result for the major cocaine metabolite in urine.

My question is this: Is the pharmacodynamic mechanism through which these false positives emerge known; and (if it is) what is it? Is it test nonspecificity, or substances and conditions producing the same metabolite, or ... what?

Thank you


Thank you for visiting NetWellness. It is beyond the scope of NetWellness to answer questions concerning drug screens. However, the article Drug Testing may help you better understand the drug screening process and options you may have if you feel your screen has been erroneous.

For more information:

Go to the Addiction and Substance Abuse health topic, where you can:

Response by:

Brenda (Rose) Clark, MPH, MA
NetWellness Program Manager
College of Public Health
The Ohio State University