There are some quirky exceptions to these rules, though. For instance, if you have a medical condition that requires you to carry a certain liquid, you're usually good to go. And, fun fact: breast milk and formula are exempt from the 3.4-ounce rule - yay for new moms! But don't try to sneak in a larger container of shampoo just because you have a dry scalp - that won't fly.
Airline Carry-on Luggage Size: Everything You Need to Know - The Points Guy
The EU and US have slightly different rules, which can get confusing when you're traveling between continents. But, in general, it's all about being prepared and aware of the rules. So, do your research, and don't get caught out with a forbidden flask of perfume - not cute.
