Before you go be sure to get enough prescription drugs for your entire stay and an extra supply just in case. Bring the prescription notes from your doctor with you to show as proof that you are allowed to have the prescribed medication if you get questioned. All prescriptions medications must be in their original containers and labeled clearly in your name to avoid any problems with local authorities.
US prescriptions justify you having the medications; however, they are not valid in pharmacies overseas. For refills of prescription drugs, you will need to visit a local doctor who will most likely be able to write you a prescription.
Important Note: Certain prescription drugs (such as Adderall, commonly used for ADD or ADHD) that are legal in the US are illegal in various countries. Please be aware of any applicable restrictions and contact the US Consulate/Embassy for further details.