An aerosol can is basically a metal container holding a liquid product and a propellant gas. When you press the nozzle, the gas expands, forcing the liquid out as a fine mist. So technically, you’re carrying liquid inside a pressurized package—which is why security treats them like liquids.
Fun fact: The first aerosol patent was granted in 1927 to a Norwegian engineer, but it took decades to perfect the nozzle. Today, you can thank that innovation for everything from bug spray to whipped cream in a can.
What About That “Full-Size” Sunscreen?
Here’s where it gets practical. You can bring full-size aerosols (like sunscreen or shaving cream) in your checked luggage, but restrictions apply. The TSA says containers over 3.4 ounces—or 100 milliliters—must be packed in your larger bag. For carry-ons, anything that sprays must fit in that tiny quart bag, period.
Pro tip: Always check the label. Products labeled “non-flammable” or “non-pressurized” (like dry shampoo powder) might slip through, but don’t rely on it. If it hisses when you press the button, it’s probably a liquid in disguise.
