With all the Transportation Security Administration’s rules regarding air travel, it can be confusing to know what you are and aren’t allowed to carry onto a plane -- and in what quantity. For example, you can take a sandwich in your carry-on bag, but not yogurt. Snow globes smaller than a tennis ball are allowed, but those larger are not. With so many complex rules, travelers might question whether solid deodorant is technically considered a gel -- and therefore not allowed in sizes greater than 3.4 ounces.

Solid Deodorant

The official answer, according to the TSA’s blog, is that you can bring solid stick deodorant “of any size” in your carry-on luggage. In other words, it qualifies as a solid rather than a gel or liquid. However, there have been reports of local screening agents who do not understand this distinction. To be safe, consider buying a travel size of your preferred solid deodorant and putting it in your baggie along with any other gels and liquids. While this is not required, it may help expedite your screening process.

Other Deodorants

Gel and aerosol deodorants are a different story -- they do not qualify as solids. Instead, you must put them in your quart-sized clear plastic baggie along with any other gels and liquids you wish to carry onto the plane. To go this route, your deodorant’s original size must be 3.4 ounces, or 100 ml, or less. It doesn’t matter if it's partially used; screening agents care about the original package size, not how much remains.

Other Personal Care Items

Many other personal care items, such as hair gel, mouthwash, toothpaste and even gel-cap pills, fall into the gels and liquids category. This doesn’t mean you are absolutely prohibited from carrying them onto your flight. However, the original package amount must be 3.4 ounces or less for each item, and all of these items must fit together into a single one quart zip-top bag. Make sure you bag them ahead of time to spare yourself hassle and annoyance when going through security at the airport.

Cosmetics

Like deodorant, cosmetics can be confusing when it comes to carry-ons and screening regulations. Believe it or not, many simple, everyday cosmetics count as gels or liquids and must be treated accordingly. This includes mascara, lipstick, lip gloss and liquid foundations.

The 3-1-1 Rule

If all these numbers and regulations get a bit confusing, keep in mind the TSA’s 3-1-1 rule for liquids and gels. The “3” refers to the size of your liquids and gels -- keep them under 3 ounces; technically you can go up to 3.4, but that isn’t as catchy. The first “1” refers to the size of your permitted baggie: one quart. This baggie has to be clear plastic and have a zip top. The final “1” refers to the number of these bags each passenger can have: one. Take care not to overfill your bag, because it has to be able to close.