An autoinjector having a body (1, 2), a reservoir (S) with piston, and a piston rod (5) movable between rest and injection positions. An actuator spring (6) urges the piston rod (5) towards its injection position. The autoinjector has a force-adjustment system (7, 8) exerting a force (F2) on the piston rod (5), adding to the force exerted by the spring (6) at the beginning of injection. Two pivot members (7) co-operate with the piston rod (5) and are connected together by two resilient elements (8). The body (1, 2) includes a sleeve (3), the pivot members (7) being pivotally mounted on the sleeve (3) to pivot about stationary pins (79). The autoinjector includes an end-of-injection indicator formed by and/or fastened to said sleeve (3) and includes an indication portion movable and/or deformable relative to the body (1, 2) to co-operate with a viewing window.
