The invention refers to an auto-injector (1) and to a method for operating it, the auto-injector comprising:- a tubular chassis (2),- a carrier subassembly comprising a tubular carrier (7) slidably arranged in the chassis (2), the carrier (7) containing a syringe (3) with a hollow injection needle (4), a drive spring (8) and a plunger (9) for forwarding load of the drive spring (8) to a stopper (6) of the syringe (3),- a wrap-over trigger sleeve (12) arranged over the distal end (D) of the auto-injector (1), the trigger sleeve (12) extending at least almost over the whole length of the auto-injector (1),- a control spring (19) arranged around the carrier (7),- first interlock means (20, 22, 23, 24) for coupling a proximal end of the control spring (19) to either the carrier (7) for advancing it for needle insertion or to the chassis (2) for needle retraction,- second interlock means (11, 13, 15) arranged for releasing the drive spring (8) for injection,- third interlock means (16, 17, 18) arranged for coupling the chassis (2) to the carrier (7) for joint axial translation relative to the trigger sleeve (12),- fourth interlock means (21, 25, 26, 28) arranged for coupling a distal end of the control spring (19) to either the carrier (7) for needle retraction or to the trigger sleeve (12) otherwise.
