Review of parenteral sulfite reactions.

Sulfiting agents are commonly used in parenteral emergency drugs, including epinephrine, dexamethasone, dobutamine, dopamine, norepinephrine, phenylephrine, procainamide, and physostigmine. Published anaphylactic or asthmatic reactions have been associated with sulfited local anesthetics, gentamicin, metoclopramide, doxycycline, and vitamin B complex. The reactions differ from those caused by foods, in that they have a rapid onset, have no predilection for steroid-dependent asthmatics, and do not always coincide with a positive oral challenge. The mechanism is unknown, but may involve a dose-related reaction with disulfide bonds on sympathetic and parasympathetic receptor membranes. Patients with a history of positive oral challenge to 5-10 mg of sulfite may be at increased risk of developing a reaction to parenteral sulfites. Despite documentation of sensitivity, sulfites should not be withheld from patients experiencing a life-threatening emergency. Non-sulfited alternatives are often available, and should be used preferentially.