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Addiction and Substance Abuse

False positive for cocaine



I recently tested positive for cocaine and I know that I haven`t used. At first it really blew my mind and I started doing some research. I am HIV + and have Hep. C I also take quite a few medications including Amoxicillin. I read that Amoxicillin and certain other antibiotics can give a false positive, is this true?


While it is uncommon for false positive urine tests to be reported for cocaine, you have identified two potential factors causing erroneous results.  Liver disease as well as Amoxicillin are both reported to have caused false positive tests for cocaine.  Diabetes and kidney disease have also been associated with false positive urine screens for cocaine.

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Response by:

Tom Hartwell Pepper, MD Tom Hartwell Pepper, MD
Medical Director of Ohio State University Addiction
College of Medicine
The Ohio State University