As far as international is concerned (please include Canada) original bottles are a must. I've had US Customs paw through pills to such a degree that they were too dirty to use as far as I am concerned.

I am less careful domestically, but I make sure that I have essential medications in more than one place in case as bag/purse etc. goes missing.

Also, for heaven's sake, don't put all your supply of medications into a checked bag!

I haven't had any problems with security.