All medications should be packed in the carry on bag. We have tried every type of system when packing medications. I will give you my observations. I know people who carry the original bottles (all 40 or more of them). Some people are on a lot of medications and many of the medications are in oversize bottles. There is a fear that the airport "inspectors" will want to analyze the medications, so it is necessary to have them in their original bottles. I used to carry the bottles with us. Of all the trips, only once did I even have an "inspector" try to open a bottle to look. His supervisor told him to close the bottle. I got the impression that he was out of line opening the bottle. Always carry a complete list of medications, using the name appearing on the bottles, as well as the dosage. This is more for your benefit if you need the information abroad than it is for the security "inspector" at the airport. With the list of medications, include your physicians' telephone number(s), so that you won't have to search for the information if you need it. Make sure you know which color pill matches the medication on the list, so that if someone asks you to identify the medication, you can. (I don't expect this to happen, but it can make you look intelligent, if it does.)
If you are going for 3 weeks, pre-pack at least 3 weeks' worth of medication in your pill organizers. If I am going for 3 weeks, I will usually take 4 weeks' worth of organized medication.
Bottom Line: Organize your medication, know what you have, take a list of the medications along with doctor information, and whatever you do, wrap plastic wrap securely around the pill organizers before you leave home, so that all of the little lids don't pop open and spill the pills inside of the Ziploc bag you place the organizers in. They are retrievable, but it is a pain. (I know.)