Zion, the syringe is not perfect and so it traps air bubbles. For me, it's just a single bubble, usually quite small. Acc to nurse, it is fine. The only concern is if the bubble is too large, then injection volume will be slightly less than intended. You can repeat a few times (and flick the syring barrel) until the bubble is acceptably small. Or try to suck in more air, hopefully the air bubbles join together, and eject them plus any excess liquid. Hope this helps.