Percocet is a combination of aspirin (acetaminophen) and Oxycodone. So the question is “does Oxycodone show up in urine”? Oxycodone is an opiate and opiates are one of the substances tested for in urine drug screening. Opiates taken within a day or three of the test most likely will show up. However, some levels are not reportable in some states or situations. Just like alcohol, there are acceptable levels. In some situations, if you do test positive and you are within acceptable limits the entity requesting the test may legally be able to ask you for your medical history supporting the prescriptions legitimacy.