Provided are medication injection supervisor devices for use with prefabricated injection pens. A medication injection supervisor device may include a universal header having one or more attachment features for attaching the header to a prefabricated injection pen. The attachment may be removable or permanent. Some examples of removable attachments include a sleeve for positioning around the pen, a slot for receiving a ridge of the pen, a cavity for receiving a clip or a specially configured pin of the pen, and two rings into which the pen may be received. Some examples of permanent attachments include integrated bodies of the pen and universal header and glue. The medication injection supervisor device may also include an electronics assembly housed by the universal header, a sensor for automatic detection of an injection, a display for viewing injection data, and one or more buttons for manipulating the injection data, such as resetting the time.
