Local anesthesia uses medicine (anesthetics) to block pain from a part of the body. The medicine affects only the area near where the medicine was injected or applied.
How it's done
Anesthesia medicines are usually given by injection into the area that needs to be numbed. They may also be applied onto the skin or mucus membranes as a liquid or gel or given as eyedrops. This is called topical anesthesia.
Serious problems (including allergic reactions) are very rare. But if the medicine is given in higher doses or if it enters the bloodstream, there can be some side effects. Examples include ringing in the ears, dizziness, and a metal taste in the mouth.