Do you need to inject air into a vial of medicine each time the vial is used or just the first time the vial is used?

[NRSKarenRN, BSN, RN]

Inject air into a vial EACH AND EVERY TIME a vial is accessed equal to the amount of volume to be withdrawn after swabbing with alcohol pad on vial stopper to remove contaminents.

Injecting air into a vial plays a important role in the process of withdrawing liquid medication. Without this step, a vacuum forms inside the vial, making it difficult to extract the required dose. By introducing air, the pressure inside the vial equalizes, allowing the liquid to flow smoothly into the syringe. This technique ensures accurate dosing and prevents unnecessary strain on the syringe, especially with thick liquid suspensions. Tap out any air bubbles at top of syringe and confirm accurate dose prior to withdrawing syringe from vial.

More info: Why Do You Inject Air into Vial?

Example for my dogs insulin of 10Units: I clean off top of vial with alcohol pad, pull back on the syringe plunger to 10 unit mark and insert needle into vial while keeping it upright then push the plunger in till all air injected. Invert vial then pull back on plunger until insulin fills syringe to 10 unit mark. Check for air bubble, expel any bubble and pull back med to 10u mark.  Ready to inject dog with SQ med -- if he didn't turn tail and hide in his crate house!

[offlabel]

The smaller the vial, the less important it is and the smaller the volume of the desired dose, the less important it is....and it is not necessary if a glass ampule is the source of the medicine...seems intuitive but not to everyone...