Auto-injector

An auto-injector with an interlock mechanism for defining an operation sequence in a manner to allow a lateral trigger button to be operated when a proximal end of the auto-injector is pressed against an injection site. A detector is arranged inside an elongate housing of the auto-injector at the proximal end and slidable in longitudinal direction and biased by a detector spring. A dog is arranged at the trigger button and wherein at least one longitudinal bar is provided, at least one of the bars slidable in longitudinal direction and coupled to the detector for distal movement. A recess for the dog is provided in the bar for allowing the trigger button to be pressed when the detector means is being pushed into the auto-injector and wherein otherwise the dog is engaged with the bar in a manner to prevent the trigger button from being pressed.