Most inhalers currently on the market are not flammable, but they are pressurized canisters that can explode under high heat. The propellants used in today’s metered-dose inhalers (MDIs) are classified as non-flammable, though a newer propellant being introduced to reduce environmental impact is technically flammable. Understanding the difference matters for safe storage, travel, and disposal.
Current Inhaler Propellants Are Non-Flammable
Metered-dose inhalers, the most common type with a pressurized canister, use hydrofluoroalkane (HFA) propellants to push medication into your lungs. The two propellants used in virtually all current MDIs, known as HFA-134a and HFA-227ea, are non-flammable gases. They won’t ignite if exposed to a spark or open flame under normal conditions.
Dry powder inhalers (DPIs), the other major type, don’t use propellants at all. You inhale the powdered medication using your own breath. Without a pressurized canister or chemical propellant, DPIs carry no flammability or explosion risk.
A New Propellant Changes the Picture
The inhaler industry is shifting toward a propellant called HFA-152a, which has a much lower global warming potential than the current options. There’s a catch: HFA-152a is technically classified as a flammable substance. Pharmaceutical companies are working through the regulatory and engineering challenges of using a flammable propellant in a device people hold near their face, but inhalers using HFA-152a are already in development. If you encounter one in the future, it will likely come with specific safety labeling about heat and open flames.
Heat and Explosion Risk
Even though current propellants won’t catch fire, the canister itself is a pressurized metal container. That’s the real safety concern. Albuterol inhalers can explode when stored in temperatures above 120°F (about 49°C), according to the Asthma and Allergy Foundation of America. A car parked in direct summer sun can easily reach or exceed that temperature, especially on the dashboard or in the glove compartment.
If you accidentally leave an inhaler in a hot car for a short time, it probably won’t explode immediately. But repeated heat exposure can weaken the canister, degrade the medication, and alter the dose you receive. The safest approach is to keep inhalers at room temperature and bring them with you rather than leaving them in vehicles during warm months.
Disposal Hazards
The biggest real-world flammability concern with inhalers isn’t using them. It’s throwing them away improperly. The World Health Organization guidelines state clearly that disposable aerosol canisters and inhalers should not be burned or incinerated, because high temperatures may cause them to explode. This can injure waste handlers or damage incineration equipment.
Even “empty” inhalers still contain residual propellant under pressure. Puncturing a used canister can release that remaining gas rapidly. Many pharmacies accept used inhalers for proper disposal, and some areas classify pressurized MDI canisters as hazardous waste that shouldn’t go in regular household trash. Check with your local pharmacy or waste management program for the recommended option in your area.
Practical Safety Tips for Everyday Use
- Using your inhaler near flames: With current HFA propellants, normal use near a gas stove or candle is not a fire hazard. This will change if you’re prescribed an inhaler with the newer HFA-152a propellant.
- Storing in your car: Never leave an inhaler in a vehicle on a hot day. Temperatures above 120°F can cause the canister to burst.
- Air travel: Pressurized inhalers are allowed in carry-on luggage. The pressurized cargo hold of a plane is temperature-controlled, but keeping inhalers with you avoids any risk from extreme conditions.
- Disposing of old inhalers: Don’t throw them into a fire, campfire, or fire pit. Don’t puncture the canister. Return them to a pharmacy or follow local hazardous waste guidelines.