How do EpiPens work?

Inside the pocket-sized pens with the ability to save lives

(Image credit: Intropin/ Wikimedia Commons)

For those with severe allergies, an EpiPen should always be close to hand in case of an anaphylactic shock. Caused by an intense immune response to allergens such as a bee sting or peanuts, anaphylaxis occurs quickly after contact with an allergen. Inflammatory molecules called mediators are released by the immune system en masse, leading to the symptoms of an allergic reaction.

Swelling (particularly in the throat), wheezing and loss of consciousness are just some of the symptoms associated with anaphylaxis, but a shot of epinephrine (adrenaline) from an EpiPen will treat the spectrum of reactions. Epinephrine increases the heart rate, relaxes muscles and reduces the aggressive immune response, so it’s a good job this potentially life-saving medication comes in a handy pocket-sized pen.

(Illustration by Jo Smolaga)

This article was originally published in How It Works issue 109

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