A plunger activated capping system is disclosed which includes a syringe body defining a fluid reservoir, a plunger assembly including a plunger rod and a sealing member supported on the plunger rod, and a luer cap releasably secured to a distal end of the syringe body. The luer cap includes a luer-type connector member and a fluid outlet. A luer cap plug is releasably supported on a distal end of the plunger rod at a location distally of the sealing member. The luer cap plug is movable into engagement with the luer cap to seal the fluid outlet of the luer cap upon advancement of the plunger assembly from a retracted position to an advanced position. The plunger assembly is configured to effect disengagement of the luer cap from the distal end of the syringe body when the plunger assembly is moved to the advanced position.