The TSA enforces strict baggage rules for liquids in carry-on bags. All liquids, gels, and aerosols must be in containers of 3.4 ounces (100 milliliters) or less. These items should be placed in a single, quart-sized, clear, plastic, zip-top bag. Only one bag per passenger is allowed. Larger containers must be checked in baggage. Exceptions apply for medically necessary liquids with proper documentation.