Local anesthetic allergy

Reaction signs & chairside management

• Allergic-type reaction to an anesthetic injection or numbing gel (hypersensitivity)

  True IgE-mediated allergy to amide anesthetics (lidocaine, articaine, mepivacaine) is exceedingly rare; most reported "allergies" are actually to ester-type agents (e.g. benzocaine, procaine), to the sulfite preservative (sodium metabisulfite) in cartridges containing epinephrine, or a vasovagal/anxiety reaction misattributed to the drug.

  Clinical management: Confirm the specific agent and reaction history; where a true amide allergy cannot be ruled out, use a preservative-free, single-dose amide cartridge and consider allergy testing before elective treatment.

• Reaction to the sulfite preservative in anesthetics that contain epinephrine (sodium metabisulfite sensitivity)

  Dental anesthetic cartridges containing a vasoconstrictor (epinephrine/levonordefrin) include sodium metabisulfite as an antioxidant; this excipient, not the anesthetic itself, is a rare cause of immediate or delayed allergic-type reactions.

  Clinical management: Ask specifically about sulfite sensitivity (e.g. reactions to wine or dried fruit, sulfite-sensitive asthma). For a confirmed sulfite allergy, use a plain (vasoconstrictor-free) anesthetic, which contains no metabisulfite, and refer any suspected anesthetic reaction to an allergist for component testing rather than labeling the patient 'allergic to all local anesthetics'.