I have had severe shoulder pain over the last several days. So I took some Norco that I had in my cabinet from a root canal I recently had. I ended up going to the doctor for the shoulder pain and I was prescribed tizanidine. I know that these two shouldn’t be taken together but I have already taken the Norco and it did not help much. I would like to take the muscle relaxer but I need to know how much of a window I need to give in order to be safe.