For the better part of two decades, we’ve limited the liquids we carry through airport security. The magic number settled upon was 3.4 ounces, or 100 milliliters, of liquid in a container—an amount that became an international standard developed by explosives experts.
As frequent travelers are well aware, bottles that are 3.4 ounces or less can be stashed into a single one-quart plastic bag, and each traveler is allowed one—in a rule that’s been dubbed the 3-1-1 liquids rule. Oversized liquids can still be packed, but need to go into checked-in baggage.
But as screening devices have become more savvy, there has been talk of those limits being eliminated, especially as a recent report said the UK will scrap the rules by 2024. “The introduction of new technologies has played a significant role in how aviation security has evolved over the past 20 years, thanks to strong industry partnerships and TSA’s agility in adopting technology that enhances security and improves the passenger experience,” a TSA spokesperson says. While there’s no timeline in place yet, the agency “anticipates the limit on liquids will be lifted in the coming years.”
So in the short run, travelers still need to limit the fluids they pack in carry-ons. But, as with all rules, there are exceptions. “TSA requires additional screening to ensure the safety of these liquids,” the spokesperson says of the items. “Travelers in this group should notify security of their medically-necessary liquids.”
In general, those exceptions need to pass a three-prong test. They need to be required during the duration of your flight or at your destination, they can’t be available at the airport in the area past security, and they can’t be available at the destination. But when it comes down to it, the TSA says on its site, “The final decision rests with the TSA officer on whether an item is allowed through the checkpoint.”
Here are some of the most common exceptions of oversized liquids that can be taken through security.
Prescription liquids, creams, and gels
Medication that has been prescribed specifically for you is perhaps the most common item that qualifies as an exception. TSA recommends that it’s clearly labeled so there's no question about what is inside. “You are responsible for displaying, handling, and repacking the medication when screening is required,” the agency’s site dictates. Depending on the situation, medication can either be screened visually or with an x-ray machine. It may also be tested for traces of explosives.
In some situations where the officers aren’t able to properly screen the item, you may be asked to open the container and transfer it to an empty container to test, or possibly dispose of a small quantity.
In cases where you would like to make sure the medication isn’t opened or X-rayed, simply inform the TSA officer. “Additional steps will be taken to clear the liquid and you will undergo additional screening procedures to include a pat-down and screening of other carry-on property,” the site says.
Liquid medications and contact lens solution
In general, liquid medications that are not prescriptions and contact lens solutions are limited to 3.4 ounces, but TSA does allow “larger amounts of medically necessary liquids, gels, and aerosols in reasonable quantities for your trip,” with the caveat you must declare them to security officers first.
Breast milk and infant formula
Passengers traveling with infants have enough to worry about on their flights—and being able to provide the little ones with the proper nourishment should not be one of those concerns. Technically, TSA categorizes breast milk and baby formula as “medically necessary liquids.” The child doesn’t need to be present for the exception.
In order to expedite the process, TSA suggests—but doesn't require—that the liquids be transported in clear and translucent bottles, so that they can be screened by the Bottle Liquid Scanners. (Those in pouches may not be able to.) While there is a chance you may be asked to open them, nothing will ever be placed in the liquid. The agency also adds that the screening process shouldn't affect the formula, but if you prefer they not be x-rayed, alternative testing means can be taken.
Baby and toddler food and drinks
In addition to breast milk and formula, food and drinks for babies and toddlers are also allowed, including puree pouches. They also technically fall into the “medically necessary” category. Water for babies is also allowed in “reasonable quantities.”
Liquid teethers
TSA also recognizes how important teethers are to babies and has “liquid-filled teethers” specifically called out as an item that can be brought through the security check.
Ice, gel, and freezer packs and other accessories to medically necessary items
Ice, gel, and freezer packs that are required to keep other medically necessary items in their required cool state are also exceptions, no matter what state they are in (solid ice or liquid gel). Additionally, IV bags or other accessories to medical supplies are also allowed.
Hand sanitizer
In the age of the COVID-19 pandemic, one major allowance was added to the list—hand sanitizer. While they may be readily available beyond security check and at your destination, the hygiene item was added, especially for use on the plane, as some experts have said that extra precautions should be taken on airplanes and airports to prevent the spread of germs.
Until further notice, hand sanitizers of up to 12 ounces are allowed since “TSA understands that COVID-19 is at the forefront on the minds of travelers, as health officials are encouraging that individuals wash their hands frequently,” the site says.
Live fish in water
Assuming your live fish in water needs more than 3.4 ounces of water, this is another exception to the rule, as long as they’re in a clear transparent containers and properly inspected by the TSA officer.
Biological specimens
Liquid exceptions can be made in the name of science. Non-infectious specimens in preservative solution can be carried through if it’s for scientific research. But they’ll need to be very specifically packed.
There can be up to 30 milliliters of free liquid in a heat-sealed inner plastic bag and then no more than one liter in the outer packaging, which needs to be marked: "Scientific research specimens, 49 CFR 173.4b applies." (Specific instructions for the regulation are here.)
Duty-free purchased items in officially sealed bags
Shopping at the airport? Those liquid souvenirs can be taken home as well, as long as they are properly sealed by the cashier in a security tamper-evident bag (STEB). The system was “developed to allow an exemption" to liquid volume rules for items purchased at duty-free airport retailers or on board an aircraft, according to the International Civil Aviation Organization.