Why did I fail A Hair test when I dont do drugs. Was it my dental work?

I have took two Hair folicle test in the past month and failed both of them. I do not use drugs of any sort and have no idea why I would test positive. I have a perscription for Hyrdocodone(Vicodon ES) and I also take Zantac for heartburn daily. I have took alot of amoxicillin due to sinus illness that I have had surgery for twice already. I also just had 3 root canals in the past 2 months and I am not sure if that is true to make you test positive but I keep testing positive for some reason. Im not sure what to do or research to clear my name and keep my job. Any advice will be greatly appreciated at this point. I am clueless.

You are taking drugs that show up in a hair follicle drug test. Are the people doing the testing aware of the prescription for Hyrdocodone (Vicodon ES)? If your job involves driving or operating machinery that requires you to be alert, that could be more of a problem than just failing the test. Take the prescription in and show it to them.