Important considerations regarding the use of local anesthetic agents include:

• While rare, allergic reactions can occur with local anesthetics, so all patients should be assessed for previous history of allergy to any of the components of the anesthetic being used.
• Children and older adults may be more sensitive to the effects of local anesthetics, especially lidocaine therefore it is important to do a thorough history prior to using a local anesthetic agent.
• Xylocaine with epinephrine must be avoided in areas where blood flow is minimized by the size and space; such as the nose, penis, fingers, ear, toes and skin flaps with minimal or compromised blood flow.
• Local Anesthetic System Toxicity (LAST) can occur when the serum levels of anesthetic agent exceed safe levels and can be caused by excessive amount of agent or injection directly into a blood vessel. Signs and symptoms include numbness of tongue and/or lips, metallic taste, tinnitus, dizziness, confusion and in extreme cases, cardiovascular symptoms related to blood pressure and heart rate. LAST can be prevented by minimizing the amount of anesthetic agent used and careful aspiration when injecting to avoid directly accessing a blood vessel.