A mechanical device for assisting medication injection is provided herein comprising a connector having a distal end and a proximal end； a piston rod locked in said connector before medication injection； a spring configured to bias said piston rod distally； a releasable restraining means configured to releasably restrain said piston rod in a locked state against said biasing of said spring, wherein, upon release of said releasable restraining means, said piston rod moves distally under force of said spring； an activation means configured to release said releasable restraining means； and a mounting means for mounting a syringe at said distal end of said connector.
