What are the side effects of too much novocain (procaine) besides numbness?

Few side effects: All local anesthetics must be given in the appropriate dose for the age and weight of the patient. In the right dose, these medications have few if any side effects. Sometime Epinephrine added to prolong the effect can produce rapid pounding heart beats and a sensation of anxiety. Very high doses could cause dizziness, ringing in the ears, seizues, or other problems.

Systemic: Side effects such as jitters, ringing in the ears, metallic taste in the mouth, irritability, seizures and eventually heart rythmn problems can occur.