Illegal drugs and narcotics, as these are strictly prohibited by law in most countries. Firearms and ammunition, as well as any replicas or imitations. Explosives and flammable items, such as fireworks, gas, and aerosols. Poisonous and toxic substances, including pesticides and certain chemicals.

Under 2026 international aviation safety standards, the list of items forbidden in "hold" (checked) luggage is primarily focused on fire hazards and explosive risks. The most common forbidden item is the spare lithium-ion battery (including power banks), which must always be in carry-on luggage because of the risk of thermal runaway, which is easier to manage in the cabin than the cargo hold. Other strictly prohibited items include "strike-anywhere" matches, lighters (except one on your person), flammable liquids or solids (like gasoline or camping fuel), and compressed gases (including many aerosol sprays that aren't personal toiletries). Explosives, including fireworks and flares, are universally banned. Additionally, some airlines in 2026 have specific restrictions on "smart luggage" with non-removable batteries. Oxidizers, poisons, and corrosive materials (like bleach) are also prohibited, as a leak could compromise the aircraft's structure or electronic systems mid-flight.