Adjustable volume syringes, and systems and methods for using the same, are disclosed. An adjustable volume syringe may include a delivery syringe, a reservoir syringe located at least in part within the delivery syringe, and a reservoir plunger located at least in part within the reservoir syringe. The delivery syringe may be configured to contain a first amount of a fluid, and the reservoir syringe may be configured to contain a second amount of the fluid. An administration amount of the fluid may be determined at or prior to an administration time, and the first amount of fluid in the delivery syringe may be adjusted to equal the administration amount by adding fluid from the reservoir syringe to the delivery syringe or by withdrawing fluid from the delivery syringe to the reservoir syringe. The administration amount of fluid may be dispensed to a patient at the administration time.
