2. Flammables. While flammables may sound as obviously prohibited as firearms for airplane carry-on, they're actually not so cut and dry. Flammable liquids like butane, chlorine, and gasoline are banned on board (and in checked luggage), as are fireworks and explosive toys like bang snaps and blasting caps.

Airline bans focus heavily on fire prevention and hazardous materials. In 2026, the TSA has strictly banned cordless curling irons and flat irons powered by gas or butane cartridges from checked luggage due to fire risks; they must be in carry-on bags. Other prohibited items include flammable liquids (paints, fuels, high-proof alcohol over 70% ABV), explosives (fireworks, flares), and compressed gases (propane, CO2 cartridges unless for life vests). Lithium batteries are generally banned from checked bags and must be carried in the cabin. On the agricultural side, U.S. Customs and Border Protection (CBP) bans many fresh fruits, vegetables, meats, and dairy products from international locations to prevent pest infestations. Sharp objects like knives and large tools are banned from carry-on bags but allowed in checked luggage, while items like "toy replicas of weapons" are banned from cabins to avoid security confusion.