If you’ve seen the videos of teenagers spraying deodorant cans at lighters and creating fireballs, you already know the answer — but the science of why aerosol deodorant is flammable is worth understanding, especially for safety around heat sources.

Most aerosol deodorants and antiperspirants are flammable. The propellant in aerosol cans — typically butane, isobutane, or propane — is a highly flammable gas. When you spray the can, you’re releasing a mist of this flammable propellant along with the active ingredients. Near an open flame or high heat, this mist can ignite.

Why Aerosol Cans Are Dangerous in Heat

Two risks come with aerosol cans:

1. The spray itself: Spraying near an open flame or spark creates an immediate fire risk — the flammable propellant ignites, causing a brief fireball. This is the source of the “deodorant flamethrower” trick that causes burn injuries every year.
2. The can under heat: Aerosol cans are pressurized. In a fire, or even left in a hot car (above 120°F / 49°C), the internal pressure increases dramatically. The can can rupture violently or, in worst cases, become a projectile. This is a well-documented hazard in vehicle fires and house fires — aerosol cans can explode, injuring or killing firefighters.

Safe Use and Storage

• Never spray aerosol deodorant near candles, lighters, gas stoves, or pilot lights
• Don’t leave aerosol cans in a car on hot days or near any heat source
• Don’t puncture or incinerate cans — even empty cans retain residual propellant
• Store at room temperature, away from direct sunlight

Stick and Roll-On Deodorant

Non-aerosol deodorants (stick, roll-on, cream) don’t contain flammable propellants. They may contain alcohol as a base ingredient, which has some flammability, but the risk is minimal compared to aerosol versions. For related reading on aerosol safety, see our article on whether spray paint is flammable.