this is commonly used with to inject substances into the body or extract fluids from it. This syringe does not appear to contain anything."
It can be used to extract blood for blood testing and inject medicine from Injection Vials.
To extract blood take the syringe in your hand and use it on yourself or a player in front of you.
Syringes are not needed in 0.32.114557 as blood testing doesn’t require them and Injections Vials have no real effect.
Syringes are medical loot and spawn regularly in hospitals and medical centers. There is also always a syringe in new first aid kits.