Expert: Ronald Levy, M.D. - 4/1/2008

Question
Thank you for taking the time to read this for me.  Over 20 years ago I had a root canal using lidocaine.  I received my injection of lidocaine and during the procedure I started to feel funny, maybe weak or dizzy. The second visit, after the injection, I felt faint and much sooner. Believe it or not no one made note of these reactions and I was given it again on my third and final dental visit.  That time I felt very strange and weak and faint.  I could not lift my arm or move and my eyes closed and I was unable to open them and then I went unconscientious.  When I awoke there was a doctor in the room and I had blankets on me.  I did however finish my root canal at that visit, after all, I was still numb! I was told never to have lidocaine again.  My present dentist seems to think I had a vaselvagal reaction but since each injection it became progressively worse and I had no heart palpitations I disagree.  But what did happen?
Since then when I needed dental work I was given carbocaine.  Three years ago during a routine filling appointment I was given 1/2 of a carpule of carbocaine and when I was still having discomfort I asked for more.  After receiving the other 1/2 carpule I started feeling that weak, fainting feeling again and as it began to subside my heart would pound so hard it hurt each beat.  This only lasted about a minute or so but it really frightened me.  
Since then I have been unable to go the dentist.  I know I need some dental work since several of my teeth hurt!
Is there a reasonable explanation for these events? Is this an allergic reaction or a possible toxic reaction to these drugs? Please do you have any advice for me as to how I can possibly get my much needed dental treatment?
One more detail--I'm very drug sensitive and so was my father.  I'm allergic to many antibiotics and codeine.  I only need 1 tylenol for a headache and do not take vitamins or anything else unless absolutely necessary.

Any help you can give would be greatly appreciated but if you do not have any answer thank you for trying.

Answer
What you have doesn't sound like an allergy (which usually presents with itching, rash or breathing problems) but it is certainly unusual. Generally people who are allergic to local anesthetics are allergic to the ester-type agents (Lidocaine is an amide-type). Often what people are allergic to is the preservative. I have included a link which may explain all this better than I. If you still have questions after reading this, write again.

http://www.dentalfearcentral.org/allergy_novacaine.html

Ronald Levy, MD
Associate Professor of Anesthesiology
UTMB-Galveston