Can cocaine show up in the blood by taking Percocet and using the lidoderm patch together?

Percocet (Oxycodon )No, will show positive for "oxycodon" or high dose or frequent recent use of oxycodone may leave enough morphine in the body to be detected with "opiates" panel (morphine is not a major metabolite of oxycodone).

But Lidoderm (Lidocaine Patch) may cause false positives for cocaine. If you did not use cocaine and still came up positive, you should insist on additional GC/MS (Gas Chromatography / Mass Spectrometry) testing. Generally Labs need to confirm (usually with GC/MS, or LC/MS/MS) any "fail positive" initial test, but if you apply for job , many company doesn't pay for this confirmation test (and you are s*** up).