Systems and methods for delivering a medication to a person experiencing an emergency medical event without requiring intervention or action on the part of the person. A device encases a reservoir of medication and a delivery mechanism. Sensors in the housing sense a physical attribute of the person and circuitry monitors information collected by the sensors to determine if the person is experiencing a severe medical condition or event based on the information. An input device on or in the housing, such as a button, may be used or activated by the person if the detected condition or event is a false positive to cancel further action. If the system does not include the button or if the user does not press it in time, the system activates the delivery device and injects the medication into the person.