Most of the time, it has fluid for medicinal purposes in it. The syringe does the job of delivering the medicinal fluid into whoever needs it.
it dose because it is not sterial any more
They are made for administration of specific measurements of either insulin or the antigen for TB testing called PPD (Purified Protein Derivative). Both types of syringes are calibrated into "units"....
for putting medicine in patients
Why would you want to do that?!