False positive for pcp - drug test

I was given an on-site drug screen earlier this week and somehow came back positive for pcp. I have never touched this drug in my life. How is this possible? I take effexor xr, trileptal, and risperdal daily, could these medications have any effect on the test results?

[boogieman]

hi there. i had the exact same thing happen to me, i was also on effexor xr and risperdal. from what i was told by the lab technician at medtox (who manufactured the test), the effexor will give such a false positive. "on site" tests are not 100% accurate and such specimens when questionable need to be further analyzed through gas chromatography mass spectrometry to give absolute results. when it happened to me, i went to a private facility the next day (it was late at night when i was tested) and had a specimen collected and sent to a lab. the negative results were available within 24 hours. needless to say, i still suffered as a result of the test initially, but further analysis vindicated me of any wrongdoing. take care,  gm