What action should be taken if blood appears in the syringe during an injection?

When blood appears in the syringe during an injection, it indicates that the needle may have entered a blood vessel. The correct action in this situation is to withdraw the needle and change the injection site. This approach is essential to prevent complications, such as injecting medication into a blood vessel, which can lead to systemic side effects or complications related to the medication being administered.

Withdrawing the needle helps ensure that the injection is conducted safely, avoiding any potential harm from accidentally delivering the medication intravascularly. Changing the site allows for a new area that is free from blood vessels, which can help in achieving the intended effect of the medication without the risks associated with vascular delivery. Therefore, both withdrawing the needle and changing the site are necessary actions in response to seeing blood in the syringe.