Charlie99:As I understand it what is controlled in Mexico very closely is straight, unadulterated Sudafed/Psuedoephenephrine. If it's combined with Tylenol, antihistamines, etc. it can't as easily be used in a meth lab and doesn't raise the same sort of concerns as the pure stuff.
I always have the straight psuedophedrine (little red pills) with me and as long as you only have a reasonable amount for personal use then it's not a problem. If you are going for a week and have 5 boxes, that may raise some eyebrows.
Not sure if it's country wide, but I know that in several states they've taken anything with psuedophedrine off the shelf and you have to ask for it at the pharmacy of service counter. They also limit the amount you can purchase and you have to be over 18.
Unless your meds are a controlled substance or a narcotic, there isn't any issue with having them with you. Again, as long as you don't have more then what would be reasonable for the time you are there. For controlled substances you should have a copy of the perscription with you, not just the bottle with pharmacy label.
They've never had issue with my allergy or migrane meds that have been in small pill holders. I also carry 2 epi-pens and have not had a problem.