Epinephrine auto-injectors are medical devices designed to deliver a dose of epinephrine, a hormone that can quickly treat severe allergic reactions, known as anaphylaxis. These devices are typically used by individuals who have known allergies to substances like peanuts, shellfish, or bee stings. They are easy to use and can be administered through clothing, making them accessible in emergencies. When an allergic reaction occurs, the auto-injector is pressed against the outer thigh, and a spring-loaded needle injects the medication. This rapid delivery helps to reduce symptoms such as swelling, difficulty breathing, and low blood pressure. It is crucial for individuals at risk to carry an auto-injector at all times.