My husband took a UA at work and it came back positive for Darvocet...which isn't correct: The meds he has taken in the last 30 days are Flexeril for pulled back muscle, Ibuprophen, Tylenol, Ceftin (Antibiotic) due to a tooth being pulled the absecessed and Lortabs. Can any of these give a false positive for the Darvocet. And how can I prove it to his work place.