According to the Transportation Security Administration (TSA) toothpaste is considered to be a liquid when flying and, therefore is subject to the rules surrounding carrying liquids on flights.
Toothpaste can be included in your carry-on luggage, provided it complies with the TSA’s 3-1-1 liquids rule. This refers to the amount of liquid you plan to carry, which is limited to a maximum of 3.4 ounces (100 ml) in your hand luggage. The travel containers should be packed in a quart-sized bag within your carry on luggage. Prior to the screening process, the small bag of travel bottles should be removed in order to facilitate the screening.
Aerosols, gels, and creams also have to fit in this small bag, so it pays to be thorough in assessing what you’ll actually need while you’re away. It’s also worth remembering that most places have access to toiletries such as toothpaste and shampoo, so how much do you really need to take on your trip? Makeup, perfumes, and nail polishes can also fall into the liquid category; however, these may not be so easy to purchase whilst you’re on vacation, so it might be a good idea to try and incorporate some into your luggage.
If you need to carry bottles that are larger than 3.4 ounces, they should travel in your checked luggage. This applies whether the bottle is full or not.
These rules came into force in 2006 when the United States Department of Homeland Security raised the terror threat level to orange, following on from similar security measures in the UK.
Find out what other items are classified as liquids and how you should pack them.