Methylene blue for the treatment of refractory anaphylaxis without hypotension

Anaphylaxis is a life-threatening reaction treated primarily with epinephrine. Methylene blue, a competitive inhibitor of guanylate cyclase, interferes with the vasodilatory actions of nitric oxide. It has recently been proposed by the Joint Taskforce on Practice Parameters as an alternative treatment for anaphylaxis with hypotension that is not responsive to classical therapy. Little evidence supports its use in normotensive patients with refractory anaphylaxis. We present the case of a 43-year-old woman with severe anaphylaxis unresponsive to epinephrine. Physical examination revealed marked respiratory distress, raised oral lesions, and altered mental status but lacked hypotension. After infusion of methylene blue, symptom resolution occurred almost immediately, and intubation was spared. Side effects were minimal. We propose methylene blue as a safe treatment option for refractory anaphylaxis, whether with or without hypotension.