A dosage control syringe includes a barrel, a plunger, an adjustable lock member supported along a guide (such as a track) that is disposed along or outside an outer wall of the syringe barrel, and a stop member coupled to the plunger or the lock member. The stop member is generally aligned between the adjustable lock member and a portion of the plunger so as to limit or preclude further movement of the plunger upon engagement of the stop member with both the lock member and the plunger. The plunger is stopped by the lock member, via the stop member, when the plunger has traveled a predetermined distance set by the lock member, the distance corresponding to a desired dosage of fluid from the syringe.