A filling device is described which is configured to control the process of filling a medical or therapeutic fluid from a supply container containing the medical or therapeutic fluid into an administration container that is in fluid connection with the supply container. The filling device includes a volume control system configured to control the volume of the administration container and a pressure detection system configured to detect a pressure value related to the pressure inside the supply container. The filling device is further configured to perform the process steps of filling the administration container by: directing the volume control system to decrease the volume of the administration container, directing the pressure detection system to detect a pressure value, and directing the volume control system to increase the volume of the administration container if an increase criterion depending on the pressure value is fulfilled.