Believe it or not, I actually carry two when I travel domestically and three internationally. Pdoc has also written me out a sheaf of paper scripts for what I take, and they come along internationally, too. Totes paranoid, but here's how I reason it:

Two sets come with me domestically in zipped cases. One goes buried, hidden low in my carry-on, while one goes on top for convenience in case I need something prn.

The one on the bottom is just basically insurance in case I didn't pack the top one right, or if I spill something and can't pick it back up.

Internationally, I've had issues with grabby customs agents trying to tell me that my pills are not allowed into the country, or that they have to be inspected in some lengthy process that you can't even bribe your way out of.

That's why internationally I do my usual high/low thing with the pills in my carry-on, and I put the sheaf of scripts in the carry-on, too.

I also make sure to check a bag traveling internationally, and I stash a third set of meds in there.

What usually works if a customs guy objects to my meds is that I get real loud, wave the scripts in the air, hold up the line behind me for as long as I can, and he gets disgusted and lets me go. If he still won't give in, I give him the top set of meds and that's usually enough.

What's a real drag is if he gets all mad and wants to search your carry-on completely. He may miss your bottom pills, but if he finds them you have to apologize a ton and say how old they are, and you didn't know they were still there.

It's always worked so far.After you put the poor customs guy through all that hell, last ting he wants to do is check your suitcase.