Keep These Items out of Your Carry-On Bag

••• The Transportation Security Administration checkpoint at Denver International Airport. agents as she and others pass through the security checkpoint at the Denver International Airport. Photo by John Moore/Getty Images

Whether you're traveling domestically or abroad, bringing a bag on the plane can help you keep your important documents, breakable items, and valuables close while you travel—or avoid checking a bag altogether if you don't have too much luggage.

However, there are certain things that the Transporation Security Administration does not allow you to bring on board the airplane—no matter which airline you fly.

Additionally, there are regulations on liquids (and amounts) you're allowed to bring and certain items that are absolutely prohibited from being in your carry-on bags.

No matter which airport you go to, you should be sure to check what items you should put in your checked baggage before you arrive. Trying to carrying prohibited items may cause delays for travelers, but it can also lead to fines and civil penalties, depending on what item you're carrying. Civil penalties can range from $250 for items like tear gas, flammable liquids, and firearm parts and up to $11,000 for dangerous weapons like dynamite, gunpowder, and hand grenades.

Of course, regular travelers shouldn't have to worry about whether they can travel with such materials. Still, there are a number of regulations the TSA has on the books for what you can't bring in your carry-on or through airport security.

Common Items You Can't Bring on Board Your Flight

At one time, TSA screeners were making policies on items including pumped breast milk, liquid medicines, cigarette lighters, razors, scissors, and knitting needles, but all of these are now allowed on board domestic flights in the United States.

Since its formation in 2001, TSA has fine-tuned its list of items travelers should not put in a carry-on bag.

Now, items that are not allowed on flights or through airport security include: blasting caps; pool and spa chlorine; fireworks; liquid fuels; gel candles; liquid bleach; spray paint; tear gas; turpentine; paint thinner; ammunition or guns; self-defense weapons; mace or pepper spray; box cutters; knives; baseball and cricket bats; ski poles; hockey or lacrosse sticks; and pool cues.

Other items travelers can't take on the flights include cordless curling irons, cigar cutters, hammers and Leatherman tools, medical marijuana (even between legal states), shoe spikes, and walking sticks. You can check out the full list of items the TSA has determined are prohibited in carry-on bags on their official website.

International Travel and Foreign Regulations

While you might be allowed to board your flight from the United States to other destinations abroad, exiting and re-entering security in a foreign country can present some challenges if you're carrying items not allowed in carry-ons abroad.

For instance, in the U.S. corkscrews with no blades are allowed to be put in carry-on bags, but in Canada, corkscrews are only permitted in checked luggage. Toy weapons are banned as a carry-on in the U.K., Canada, and other countries, but only real-looking replicas are banned in the United State. Metal nail files are nearly universally banned, but nail clippers with no metal nail file are not.

If you're still concerned about what you can or can't bring on that next, you should check the resources on top global carriers' websites for recommendations on what to pack in your checked back and what you can always bring no matter where you go.

If you're still in doubt, it is a good idea to call the airline directly, as they will outline what can and can not be brought on board.

Air Canada, Air France, Alaska Airlines, ​Allegiant Air, American Airlines, British Airways, Delta Air Lines, Hawaiian Airlines, JetBlue, KLM, Lufthansa, Spirit Airlines, Southwest Airlines, and United Airlines all have specific recommendations for traveling domestically and abroad.

Edited by Benét Wilson