An injection device comprising a housing； a securing arrangement for securing the injection device against an injection site of a patient； a needle insertion mechanism configured to cause insertion of a needle into a patient when the injection device is secured against the injection site of the patient； a medicament delivery arrangement configured to cause injection of a medicament into tissue of the patient at the injection site； and a medicament retention sensor configured to detect retention of medicament in the tissue of the patient at the injection site, wherein the injection device is configured to respond to detection of swelling of the tissue of the patient at the injection site by causing provision of an alert and/or by causing suspension or halting of injection of medicament.
