Severe rattlesnake envenomation with anaphylaxis and rhabdomyolysis.

A 7-year-old boy presented to the emergency department with severe hypotension and lethargy after a rattlesnake bite. He developed anaphylaxis to antivenom and required intubation, epinephrine, antihistamines, and steroids. Severe rhabdomyolysis and myoglobinuric kidney failure developed over 24 hours, with a peak creatine phosphokinase level of 214,500 units/L. Severe hypocalcemic tetany was treated with replacement therapy. Local wound swelling was never severe and the patient had no coagulopathies. Marked motor weakness improved with antivenom administration. Because of the myotoxic and neurologic effects in the absence of fibrinogenolysis/thrombocytopenia and minimal tissue signs, as well as the similarity to a previously reported case from our area, the envenomation was most likely caused by a Mojave rattlesnake.