Except for (1) one moron at a TSA checkpoint in STL who thought she'd made the big catch when she spotted hypodermic needles in my wife's suitcase and (2) one jerk in U.S. customs at DTW, we've never been hassled or even inspected.

I have up to a week's supply in 5 seven-day containers. Domestically, that's all I ever carry.

For international trips I also carry a big (gallon?) baggie with all the original prescription bottles in case customs is looking for something to do. I keep the last 2 bottles around so I don't have to travel with too large a quantity.

My wife just travels everywhere with the actual prescription bottles.

Liquids (not much for us) just go in the 1 qt. Kippie bags. If you need large amounts of liquids (prescriptions greater than 100 ml or more than will fit in the Kippie bag), you will need to present them separately & it's a good idea to have the letter from your doctor handy. Otherwise, I wouldn't worry about the letter as long as all the prescriptions are recent & have your name on them.

Outside the U.S., the only country that has ever asked is Australia, and their wordiest response has been "keeps you alive, doesn't it".

If you're taking a lot of medications, it's a good idea to pack a list of the medications (I list mine by both brand & generic names) and keep it handy. If you end up in a hospital or ER somewhere, they'll need to know what you're taking.

Always pack your medications in a carryon. Never all it to be separated from you, i.e. gatechecked.