For air travel within the U.S., the TSA allows you to carry on all medications including liquids, gels, and aerosols, with no limit on the amount you can carry.
If you have more than three ounces of “medically necessary” drugs and they are not in a quart sized plastic bag, you are required to declare and allow a security screener to examine it. Medicines must be labeled and those in daily dosage containers will be screened.
Travel overseas is a bit trickier, as each country has its own set of rules. To avoid trouble at customs, the State Department recommends that you keep drugs in their original labeled containers and bring copies of your prescriptions as well as a letter from your doctor if you are carrying any unusual or narcotic drugs. They also suggest contacting the U.S. embassy or consulate of the country you’re visiting to find out if it’s legal to bring your particular medication into the country.