Are there side effects from novacaine or lidocaine?

Possibly: If you have an untreated heart condition, some anesthetics contain Epinephrine and could result in a racing heart. Make sure to discuss your medical status with treating dentist.

Can be: If the novocaine has epinephrine, which helps to control bleeding and duration of the affect, then some people have reactions of increased heart rate and other heart related issues. There are options that one can use. Some patients say they are allergic to the injection, but after allergy testing, it is found it is often anxiety that creates the reactions. Some just say that they can't get numb.