Can a lab urine drug test differentiate the use of tylenol (acetaminophen) #3 w/ codeine & heroin 3 days later? my drug class said i used heroin when i took tylenol (acetaminophen) 3

Retest: One of the metabolites of codeine is morphine - but not heroin. Be aware though, if it was a low yield test (ie, like the kind you buy at the grocery store) - these usually give you a positive result for any opiate. Anything more specialized (ie, laboratory study ordered by a doctor) - would use mass spectrometry and differentiate every substance independently. Hope that helps!