a positive test for amphetamines will not be falsely influenced by caffeine or acetaminophen. there is another reason. most likely that your client took an amphetamine or a medications containing a similar drug but it isn't this one.
can caffeine cause a false positive on a drug test? . a client of mine tested positive today for amphetamines using a 10 panel urine dip test. is it possible he had a false positive? he claims to take tylenol with caffeine for migraines every morning.