How Does an EpiPen Work — and Why Does It Sometimes Fail?

Fifteen-year-old Alexi Stafford died of anaphylactic shock after unknowingly eating a peanut butter cookie, and two EpiPens failed to reopen her airways

When 15-year-old Alexi Stafford went into anaphylactic shock after unknowingly eating a peanut butter cookie, her parents tried using two EpiPens to reopen her airways. But their attempts were unsuccessful, and the teen died one and a half hours after consuming the cookie and falling unconscious.

EpiPens and similar injection devices provide a life-saving dose of epinephrine, a chemical that opens up airways in the lungs of someone having an allergic reaction. But the devices do occasionally fail — most often from user error.

“There are a few things that can interfere with the effectiveness of an EpiPen,” Dr. Travis Stork, an ER physician, host of The Doctors and a member of PEOPLE’s Health Squad, says.

The first thing to keep in mind is that EpiPens expire after 18 months. “Make sure to check the pen’s expiration date and have a backup on hand if yours is close to expiring,” he advises.

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An EpiPen, used to treat anaphylactic shock. (Anda Chu/Bay Area News Group/TNS via Getty Images)

It’s also important to insert the pen properly, which can be difficult in a crisis.

“Incorrect usage can also reduce effectiveness,” Stork says. “Many patients didn’t hold it in place for 10 seconds after injection, and sometimes not injecting it hard enough can cause some of the medicine to be lost. Not injecting it into a muscle, where it can be absorbed into the blood stream as quickly as possible, can also be a factor.”

Stork suggests that people practice using tester EpiPens, which are available on Amazon.

Additionally, he says, EpiPens just provide immediate, short-term relief — it’s important to head to a hospital after using one.

“An EpiPen can improve your symptoms and in some cases may seem to resolve them completely, but you still need to go to the ER as soon as possible, even if you are feeling better,” Stork says. “Once at the hospital you will be monitored and possibly provided other courses of treatment including bronchodilators, steroids or antihistamines.”

For severe allergy-sufferers, Stork recommends keeping two EpiPens on hand at all times, because “10 to 15 percent of those with a severe food allergy will require a second dose of Epinephrine to alleviate symptoms.”

Additionally, Stork says, “It’s important that friends and family members become comfortable with recognizing signs and symptoms of a severe allergic reaction and feel confident in how to use an epinephrine auto-injector.”

“A severe allergic reaction can be very scary, but when used properly and quickly an Epinephrine auto-injector can save a life,” he says.

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