After having a random drug test for work related reasons, I began worrying about the short usage of Darvacet I was on. They were not effective so my doctor changed my prescription to Ultram. I am sure the Darvacet is still in my sysrwm, but because it is a narcotic, I am concerned it will be a drug that will be considered a problem. Inform me on the difference in Ultram and Darvacet. Thanks