An EpiPen is a medical device used to treat severe allergic reactions, known as anaphylaxis. It contains a dose of epinephrine, a hormone that quickly narrows blood vessels and opens airways in the lungs. This helps to relieve symptoms like difficulty breathing, swelling, and low blood pressure. People with known severe allergies often carry an EpiPen to be prepared for unexpected reactions. Using an EpiPen is straightforward. In an emergency, you remove the safety cap and inject it into the outer thigh. The device automatically delivers the medication, providing rapid relief. After using an EpiPen, it's essential to seek medical help, as further treatment may be necessary.