“Does local anesthesia affect your heart?”

Local anesthetics can affect the heart if given in large doses intravenously. Most local anesthetics are injected into tissue spaces and often include epinephrine to slow absorption into the vascular system. In any case, careful calculation and consideration to the ‘toxic’ dose of any given local anesthetic is given and calculated prior to any use of local anesthetics. Most uses of local anesthetic are well below limits where toxicity would come into play.

Local anesthetics used properly will not affect your heart. Occasional side effects include tremors, a metallic taste in your mouth, numbness around your mouth and tongue. Overdoses of local anesthetics can affect the heart. Some very anxious people afraid of needles may faint or decrease their heart rate (vasovagal reaction), but that is out of fear not the local anesthetic. Local anesthetics are sometimes mixed with epinephrine to increase their duration of action and reduce bleeding and blood loss. Some of the epinephrine may be absorbed into the blood stream and increase heart rate, increase blood pressure and cause an increase in anxiety. 

Best wishes,

Only if there is an overdose

Yes, local anesthetics can directly block the cardiac electrical system. In addition, local anesthetics used for regional and nerve blocks can indirectly affect the blood return to the heart due to vasodilating effects.

Or if injected directly into a blood vessel.