Xylocaine Pain
At the end of 2003, reports started surfacing from dentists in Norway (as well as Sweden and Iceland) that not only was their "Xylocain Dental Adrenalin" (i.e. lidocaine with epinephrine) not working, but it was inducing severe headaches, vomiting and pain sensitivity within an hour or two of the injections.
It is unclear from this writing what the source of the complication is, but it is believed it may have to do with a recent change of manufacturers from AstraZenica to Dentsply. Additionally, lower levels of adrenalin were being used than were supposed to be, although I don't see why that would induce these problems.
It should be noted that this is almost certainly due to a bad batch of anesthetics, rather than a literal lidocaine/epinephrine risk.