Rules are set by TSA and by the countries you travel through, and they change, so check tsa.gov before you fly. As a guide, liquids in your carry-on must be in containers of 3.4 ounces (100 ml) or less, together in one quart-sized clear bag. Medications are generally allowed in larger quantities, but pack them in your carry-on in their original labeled containers and allow extra time at security.