I have been on many pain meds for the last 5 years since a serious caar accident, including Oxycodone, percocet, demerol, mscontin,
I went to another dr and they changed me to Dilaudid and mscontin. But I have tested postitive for percocet the last 2 times which are 3 mo apart, I have not taken any percocet, for 6 months why am I testing postitive for it, this is a on the spot test, thanks

What is an "on the spot" test? Dried blood?

The cross-reaction probably relates to Dilaudid (hydromorphone) but would need to know the amount of oxymorphone being detected in order to get a specific reference.

No it is a urine test, and they said it is a traceof percocet that is being detected, what ever that means.

Still not clear on type of test.

In short, it is known that unanticipated conversions between opioids may occur. One of the most noted is an oxycodone false positive from hydrocodone.

Hydromorphone (Dilaudid) is also a breakdown product of Hydrocodone and Percocet contains oxycodone. This sequence could explain the false positive.

It always attracts my attention when it is stated that Percocet is detected because that isn't the case. It is only oxymorphone a breakdown product of the oxycodone contained in Percocet that is identified.

While these tests are procedurally simple (that's why they're used) proper interpretation of the results requires a thorough knowledge of opioid pharmacokinetics and the vast potential for cross-reactions.

Following is a resource that explains the processes more completely:

Pain Treatment Topics