Bubbles are small air pockets within the injection solution and they should not be injected. Very small amounts of air will do little damage, but larger pockets of air can cause embolisms. As long as you are not injecting into an artery, then a small amount of air can be taken up by the tissues safely. However, avoiding air bubbles when giving an injection is best, so take all of the bubbles out before giving the injection. To do this, pull back on the syringe to release air. You can also try putting more solution than you need into the syringe and discarding some of it, this will help to release the air.