What are prohibited items at security?

Who decides what can go through airport security?

At a checkpoint, the screening authority applies its own list of prohibited and restricted items. In the United States, the TSA publishes a searchable What Can I Bring? list, which runs to 495 items as of 18 October 2026, but the agency says the final decision rests with the TSA officer on whether an item is allowed through the checkpoint. [1]

For flights boarding in the United Kingdom, the UK Government says airport security staff will not let anything through that they consider dangerous, even if it is normally allowed in hand luggage. [2] That applies at the UK airport where the screening takes place, not as a universal rule for every country. [2]

The practical result is that the published list describes what is normally allowed or barred, while the officer at the checkpoint decides the individual case. [1] [2]

Why can the same item pass one airport and be refused at another?

One reason is that the security decision includes judgment about the item and the passenger’s bag, not only a yes-or-no list entry. The TSA says that even if an item is generally permitted, it may be subject to additional screening or not allowed through the checkpoint if it triggers an alarm during screening, appears to have been tampered with, or poses other security concerns. [1] UK airport security staff apply a similar safety judgment when they decide that something they consider dangerous will not pass, even if it is normally allowed in hand luggage. [2]

Another reason is that countries publish different rules. The UK Government says the rules for electronic items and devices depend on which country you are travelling to or from, and that countries outside the UK might have different rules on carrying liquids as a transit or transfer passenger. [2] It also advises passengers to check with the relevant airlines and airports before travelling. [2]

Liquid screening itself can vary within one country: the UK Government says the rules for taking liquids through security in hand luggage have changed at some UK airports and advises passengers to check with the airport before travel. [2] For more detail on that specific rule, see the airport liquids rule.

Where do airline dangerous-goods rules sit on top?

Security screening is one layer; airline carriage conditions are another. The TSA tells passengers to check with the airline for size or weight restrictions on an air mattress with a built-in pump, to check with the airline before bringing alcoholic beverages on board, and to ask the airline about ammunition allowances or fees. [1] The UK Government likewise tells passengers to check with their airline how many bags and what size bags they may take on the plane. [2]

The UK Civil Aviation Authority (CAA) groups dangerous goods, battery-powered devices, liquids, medical equipment and mobility aids among the restricted-item topics passengers should check. [3] An item can therefore clear the checkpoint and still be limited by the airline’s baggage conditions or by the law of the countries you travel to or from; the TSA notes that laws on possession of firearms vary by local, state and international government. [1] [2] [3]

Battery-powered devices have their own carriage rules, covered in the lithium battery carriage term. [3]

What does the US TSA list say about selected items?

The table below reproduces selected entries from the TSA What Can I Bring? list. It applies to United States checkpoints only and is not a global list. [1]

What are the exceptions and limits?

• Electronic devices. TSA officers may ask passengers to power up electronic devices, including cell phones; powerless devices will not be permitted onboard the aircraft, and the TSA says it does not read or copy information from the device. [1]
• Food and powders. In UK hand luggage, food items and powders can obstruct images on X-ray machines, so bags may need to be checked again manually; putting them in hold luggage can reduce delays. [2]
• Frozen items. Frozen items such as liquid, food or ice packs cannot usually be carried in UK hand luggage, with exceptions for medicines, medical equipment, dietary requirements, baby food and baby milk. [2]
• Lighters in the UK. Passengers may carry only one lighter on board, placed inside a resealable plastic bag kept on them throughout the flight; it cannot go in hold luggage or in hand luggage after screening. [2]
• Airport-specific liquid rules. Because liquid screening rules have changed at some UK airports, passengers should check with the airport before travel rather than assume one UK rule applies everywhere. [2]

Frequently asked questions

Are airport security rules the same in every country?

No. The UK Government says electronic item rules depend on which country you are travelling to or from, and that countries outside the UK may have different transit liquid rules. The TSA officer’s final-decision rule applies at US checkpoints. [1] [2]

Can an item be allowed in hand luggage but still refused at the checkpoint?

Yes. The TSA says even a generally permitted item may be subject to additional screening or not allowed if it triggers an alarm, appears tampered with or poses other security concerns. UK airport staff can refuse anything they consider dangerous even if it is normally allowed. [1] [2]

Do airline rules still apply after security?

Yes. The TSA directs passengers to check with the airline for certain items, and the UK Government tells passengers to check bag number and size with their airline. Airline conditions can add limits alongside the security list. [1] [2]

How many lighters can I take through security in the UK?

One. It must be inside a resealable plastic bag kept on you throughout the flight and cannot go in hold luggage or in hand luggage after screening. [2]

What happens if my electronic device will not power on?

TSA officers may ask you to power up electronic devices, including cell phones, and powerless devices will not be permitted onboard the aircraft. The TSA says it does not read or copy information from the device. [1]

Related pages

See the airport liquids rule, lithium battery carriage, trusted traveller programmes and the full glossary of frequent flyer terms.

Sources

Sources accessed on 18 October 2026. It covers the United States TSA screening list and UK Government and Civil Aviation Authority baggage guidance; no airline frequent flyer programme is covered, and the security rules of countries other than the United States and the United Kingdom are not covered here.

1. TSA What Can I Bring? security screening list, checked 18 October 2026
2. Hand luggage restrictions at UK airports, checked 18 October 2026
3. UK Civil Aviation Authority: guidelines for checked in and carry on bags, checked 18 October 2026