My dentist uses a numbing product that is easier on the adrenal glands than what he would normally use on his other patients.  The only drawback is it doesn’t last as long.  One time he had to be interrupted from working on me for an emergency & by the time he came back I needed more.  I like it though because it wears off so fast after you get home.  I don’t  remember the name of it but your dentist should know.  I believe it doesn’t have nonpherine or something like that.