I am using a 25 mcg generic Fentanyl patch for chronic pain. The last time I went to my pain doctor he did a drug screen and called me to say the fentanyl did not show up in my urine. I change the patch faithfully every 48 hours. I also take lortab as needed, muscle relaxers, thyroid replacement, estrogen, Lyrica, Requip, and several vitamin supplements. Could any of the other meds cause the fentanyl not to work? I have to take my fentanyl and lortab to the pharmacy for a pilll count. I am embarrassed and humiliated. I am a 58 year-old grandmother and would never dream of doing what they must think I am doing with the patches. Why would the fentanyl not show up in my urine?