Yes, toothpaste can be taken on a plane. If it is in carry-on luggage, the toothpaste must be in a container of 100ml or less and all such containers must fit into a single clear, resealable, quart-sized plastic bag due to TSA liquid restrictions (known as the 3-1-1 rule). For checked luggage, there are generally no restrictions on the size or quantity of toothpaste you can bring, but containers should be securely closed to prevent leaks. Solid toothpaste alternatives like tablets do not fall under liquid restrictions and can be carried without size limits. These regulations apply for domestic and international flights, but it's good to verify specific rules with your airline or airport when traveling internationally.