Photo of Car parking in asphalt parking lot with trees background. Outdoor parking lot

Epinephrine auto-injectors may lose potency within hours when stored in a hot vehicle, a recent study revealed.

The study, published in The Journal of Allergy and Clinical Immunology: In Practice, found that short-term exposure to heat in a car on a sunny day can decrease the concentration of epinephrine in auto-injectors.

People may be tempted to leave their epinephrine auto-injector in their vehicle while running errands or going out, but the study urges them to reconsider. If a degraded epinephrine auto-injector is used by someone, it could result in an underdosage during anaphylaxis, a potentially life-threatening allergic reaction.

“We want to urge everyone to never expose their EpiPens to high temperatures or leave them in their vehicles,” says study author Piotr Lacwik, MD. “Underdosage during anaphylaxis can have deadly consequences.”

Doctors recommend you always carry your epinephrine auto-injector – no matter where you go or what you are doing.

Epinephrine auto-injectors have a recommended storage temperature of 68-77 degrees F, although a brief stay in temperatures of 69-86 F is permitted.

The study was conducted in Poland during the month of August. Nine EpiPens were placed in a black sedan in locations with no direct sunlight – the glove compartment, trunk and cabin shelf under the rear window. The auto-injectors were left inside the car for 12 hours; temperatures inside the car eventually reached a high of 143.7 degrees F.

After 12 hours, the epinephrine auto-injectors did not show any change in solution appearance and they remained functional. When the solution was analyzed, however, there was significant reduction in concentration of epinephrine, particularly in the auto-injectors placed in the glove compartment and cabin shelf.

If an epinephrine auto-injector is kept in hot temperatures for an extended period of time, they should be replaced immediately.

Other epinephrine storage tips include:

  • keeping the pack of two auto-injectors together
  • using a storage case
  • making sure the devices are not expired

The study notes that epinephrine storage in outdoor environments is a growing concern due to global warming caused by climate change.