An auto-injector having a body (1) receiving a reservoir (S) and including a piston (P); a piston rod (5) movable between a primed position and an injection position in which the piston rod (5) has moved the piston (P) to inject fluid into an injection site; and a visual, audible, and/or tactile indicator device for indicating that the autoinjector may be removed from the injection site. The autoinjector includes a retarding system to delay actuating the indicator device relative to the end of injection and that includes a dashpot (16), a shear member (19) and a fluid. The dashpot or the shear member is rotatably mounted in the body and the other is stationary in rotation, the turning of one relative to the other being braked by shearing the fluid contained in the dashpot. The dashpot and shear member include projections that impede the flow of the fluid.