Add-on device for an injection device

An add-on device for an injection device, wherein the injection device comprises a barrel filled with a medicament and sealed by a stopper, wherein the stopper is movable relative to the barrel in a distal direction for expelling a dose of the medicament and wherein the injection device comprises a machine-readable identifier attached to or integrated into the barrel or a housing of the injection device, the add-on device comprising:

• a body,
• a fastening structure connected to the body or integrated into the body and configured to detachably connect to the stopper,
• an electronic module inside the body, the electronic module comprising a reading unit operable to read information stored in or provided by the machine-readable identifier,
• wherein when connected to the stopper, the body and the fastening structure are configured to transfer a user-exertable driving force onto the stopper to induce a movement of the stopper relative to the barrel.

An injection system comprising:

• an injection device, the injection device comprising:
• a barrel filled with a medicament and sealed by a stopper, wherein the stopper is movable relative to the barrel in a distal direction for expelling a dose of the medicament,
• a machine-readable identifier attached to or integrated into the barrel or a housing of the injection device, and
• an add-on device, comprising a body, a fastening structure connected to the body or integrated into the body and configured to detachably connect to the stopper, and an electronic module inside the body, the electronic module comprising a reading unit operable to read information stored in or provided by the machine-readable identifier,
• wherein when connected to the stopper, the body and the fastening structure are configured to transfer a user-exertable driving force onto the stopper to induce a movement of the stopper relative to the barrel.

A method of monitoring use of an injection device including the steps of:

• providing the injection device, wherein the injection device comprises a barrel filled with a medicament and sealed by a stopper, wherein the stopper is movable relative to the barrel in a distal direction for expelling at least a dose of the medicament and wherein the injection device comprises a machine-readable identifier attached to or integrated into the barrel or a housing of the injection device,
• providing an add-on device comprising a body, a fastening structure connected to the body or integrated into the body and configured to detachably connect to the stopper, and an electronic module inside the body, the electronic module comprising a reading unit operable to read information stored in or provided by the machine-readable identifier, wherein when connected to the stopper, the body and the fastening structure are configured to transfer a user-exertable driving force onto the stopper to induce a movement of the stopper relative to the barrel;
• and
• reading information stored in or provided by the machine-readable identifier through the reading unit.