A syringe including a retractable needle comprising: a barrel having a fluid chamber defining a longitudinal axis, an inside surface, a proximal shoulder located on the inside surface,-a proximal end, and a distal end adapted to be attached to a needle and a ceiling located on the inside surface and adjacent the distal end; a plunger rod having a distal end and proximal end, the plunger rod adapted to slidingly engage the inside surface of the fluid chamber, the plunger rod including a hollow inner sleeve slidably engageable with a hollow outer housing, the inner sleeve and the outer housing being axially moveable with respect to each other upon activation of a decoupling element associated with the plunger rod; and a compressible stopper mounted on the distal end of the plunger rod, the stopper including a distal face and an outer wall surface, the stopper being configured such that when distal force is applied to the plunger rod, the stopper is compressed in the direction of the longitudinal axis in an amount to allow distal movement of the plunger rod along the longitudinal axis a distance sufficient to permit activation of the decoupling element, causing the inner sleeve to decouple from the outer housing and move distally with respect to the outer housing and retraction of the needle within the syringe barrel, characterized in that the outer housing including at least one window extending axially through the wall adjacent the proximal end of the plunger rod, the inner sleeve of the plunger rod including at least one flexible finger adapted to be flexed inwardly, the flexible finger including a distal end, a proximal end, a distal facing ramp surface adapted to engage with the shoulder of the barrel and a proximal facing edge, the inner sleeve further including a proximal facing stop edge, the finger being sized and shaped to be received within the window, whereby the plunger includes a cutter mounted at the distal end of the inner sleeve disposed to cut through webbing and stopper to expose a cavity in the inner sleeve when the inner sleeve is released from the outer housing. a barrel having a fluid chamber defining a longitudinal axis, an inside surface, a proximal shoulder located on the inside surface,-a proximal end, and a distal end adapted to be attached to a needle and a ceiling located on the inside surface and adjacent the distal end; a plunger rod having a distal end and proximal end, the plunger rod adapted to slidingly engage the inside surface of the fluid chamber, the plunger rod including a hollow inner sleeve slidably engageable with a hollow outer housing, the inner sleeve and the outer housing being axially moveable with respect to each other upon activation of a decoupling element associated with the plunger rod; and a compressible stopper mounted on the distal end of the plunger rod, the stopper including a distal face and an outer wall surface, the stopper being configured such that when distal force is applied to the plunger rod, the stopper is compressed in the direction of the longitudinal axis in an amount to allow distal movement of the plunger rod along the longitudinal axis a distance sufficient to permit activation of the decoupling element, causing the inner sleeve to decouple from the outer housing and move distally with respect to the outer housing and retraction of the needle within the syringe barrel, characterized in that the outer housing including at least one window extending axially through the wall adjacent the proximal end of the plunger rod, the inner sleeve of the plunger rod including at least one flexible finger adapted to be flexed inwardly, the flexible finger including a distal end, a proximal end, a distal facing ramp surface adapted to engage with the shoulder of the barrel and a proximal facing edge, the inner sleeve further including a proximal facing stop edge, the finger being sized and shaped to be received within the window, whereby the plunger includes a cutter mounted at the distal end of the inner sleeve disposed to cut through webbing and stopper to expose a cavity in the inner sleeve when the inner sleeve is released from the outer housing.