I have been taking Hydrocodone as needed with a prescription on and off for a month for tooth pain. I have a drug screen and want to know if I will pass. I don't take them every day but have had to the past few days and wonder if I will be questioned as to why my script is a month old. It is that old because I don't need them daily. Any advice? Also out of curiosity are drug screens able to tell the amount of a drug in your system?