What is a potential side effect of using lidocaine with epinephrine?

Using lidocaine with epinephrine can lead to tissue necrosis as a potential side effect. The addition of epinephrine, a vasoconstrictor, is intended to prolong the effects of lidocaine by reducing blood flow to the area. However, if the blood supply is too restricted, it can lead to ischemia and subsequent necrosis of the surrounding tissue. This is particularly concerning in areas with end-artery blood supply, such as digits or the nose, where vasoconstriction can negatively impact the tissue's viability. As a result, careful consideration must be taken when using lidocaine with epinephrine, especially in areas where blood flow is already compromised or in patients with conditions that may affect circulation.