A method for operating an infusion device (1) for administering a medical fluid to a patient comprises: receiving a syringe (2) in a receptacle (11) of the infusion device (1)； moving, using an electric drive device (141), a pusher device (12) in a pushing direction (P) for acting onto a piston (21) of the syringe (2) received in the receptacle (11)； and obtaining, using a sensing device (171), a sensing signal indicative of a measured force (F) acting in between the pusher device (12) and the piston (21) of the syringe (2). Herein it is provided that, at the beginning of moving the pusher device (12) for acting onto the piston (21), a startup routine is executed in which in a first phase the electric drive device (141) drives the pusher device (12) to move at a first velocity (V0), and if by means of the sensing signal a drop in the measured force (F) acting in between the pusher device (12) and the piston (21) of the syringe (2) is observed, the electric drive device (141) is controlled to drive the pusher device (12) to move at a second velocity (V1) different than the first velocity (V0). In this way a method for administering a medical fluid to a patient is provided which allows for an efficient quickstart procedure.
