A RARE CASE OF PROTRACTED ANAPHYLAXIS CAUSED BY ACETAMINOPHEN

Abstract

<h3>Introduction</h3> Acetaminophen is a rare but recognized etiology of anaphylaxis. We present an unusual case of protracted anaphylaxis requiring intensive care unit (ICU) monitoring following intravenous (IV) acetaminophen. <h3>Case Description</h3> A 49-year-old female with a history of ovarian cancer presented to the emergency department with pruritic urticarial rash, fevers, tachycardia, and relative hypotension. A sepsis workup was initiated. Hemodynamics improved with broad-spectrum antibiotics and fluids. Due to symptomatic high-grade fevers, IV acetaminophen was administered. Her rash, tachycardia, and relative hypotension worsened one hour following infusion. Despite resuscitation with diphenhydramine and fluids, she remained tachycardic and febrile, prompting treatment for suspected anaphylaxis with intramuscular epinephrine, corticosteroids, and additional diphenhydramine. Her rash and hemodynamics improved moderately. She was subsequently started on norepinephrine and transferred to the medical ICU, where she had two days of persistent tachycardia and fluctuating urticarial rash responsive to antihistamines. Infectious workup was unrevealing. She later revealed a prior history of urticaria following home oral acetaminophen. Tryptase drawn one hour after decompensation was elevated to 23.8 mcg/L (baseline 3.2 mcg/L). The diagnosis was made of IgE-mediated reaction to acetaminophen causing protracted anaphylaxis. <h3>Discussion</h3> Anaphylaxis secondary to acetaminophen is an uncommon but recognized phenomenon. An initial differential included pseudoallergic reaction, given acetaminophen can be a weak cyclooxygenase-1 inhibitor causing direct mast cell activation and urticaria; however, this does not classically cause hypotension. Overall, this presentation may represent a mixed picture of sepsis of unclear etiology with superimposed IgE-mediated reaction. It is important to recognize anaphylaxis can co-exist with sepsis and manifest with overlapping symptoms.