The present invention provides for an injection device including a syringe with a proximal end, a distal end, a needle extending from the distal end, and a plunger inserted into the proximal end. A guard is slidable on the syringe, has a proximal end, a distal end, and is biased from a first position wherein the needle is exposed towards a second position wherein the guard covers the needle. The injection device includes first and second sets of cooperating detents for retaining the guard and syringe in the first and second positions, respectively. A latch member extends proximally from the guard that is engageable by the plunger as the plunger is depressed to release the first set of cooperating detents. Upon release, a spring element biases the guard towards the second position until the second set of cooperating detents engage and secure the guard in the second position.