Anaphylaxis occurs in 1/5000-1/20,000 of anesthesia cases and may evolve with shock and cardiovascular collapse in up to 54% of cases. Mortality varies from 3% to 10%. Latex is the second leading cause of anaphylaxis during the perioperative period. We report a case of latex-induced anaphylactic shock refractory to the usual catecholamine treatment that was reversed with the aid of methylene blue. Exaggerated activation of the nitric oxide-cyclic guanosine monophosphate pathway is observed in refractory shock. Methylene blue selectively inhibits this pathway.