S4098 Bowel Regimen Gone Rogue: A Rare Case of Anaphylaxis Secondary to Over-the-Counter Polyethylene Glycol 3350

Introduction: Polyethylene glycol 3350 (PEG) is a common agent used for bowel preparation before colonoscopy or other lower GI endoscopies. It is also readily available over the counter for constipation. It is generally well-tolerated. Below, we present a case of a patient who had anaphylaxis secondary to PEG. Case Description/Methods: A 57-year-old man with coronary artery disease, hypertension, hyperlipidemia and diabetes presented to the emergency department with hypotension, nausea, and diffuse itchiness 4 hours after taking PEG for preoperative constipation. Within 5 minutes of ingestion, he developed diffuse pruritus and a rash on the arms and legs. He took oral diphenhydramine with minor relief, prompting his emergency department visit. On arrival, he was tachycardic (HR 95), tachypneic (RR 29), and hypotensive (BP 83/58-- > 77/59). Workup showed normal white blood cell count, normal hemoglobin, and normal platelets; however, lactic acid was elevated to 5.6. He was given IV methylprednisolone sodium succinate 125 mg, IV famotidine 20 mg, IV diphenhydramine 25 mg and started on an epinephrine infusion. He was admitted to the ICU where he subsequently recovered. He had surgery a few days later. Discussion: PEG is widely used for bowel preparation, with most patients tolerating it well. It is also frequently prescribed for constipation and is found in more than 1,000 FDA-approved medications, including contraceptives, antihypertensives, antibiotics, and diabetes drugs. A review of literature identified only 53 reports between 2005 and 2017 in which PEG was suspected to be the cause of an anaphylactic reaction with an average of only 4 cases per year from 2005 to 2017. Most reactions occurred during colonoscopy prep, though about ¼ occurred during constipation treatment. While rare, PEG should remain on differential as a cause of anaphylaxis, and alternative bowel regimens should be considered for patients with a history of reaction. Options without polyethylene glycols or polysorbates include sodium picosulfate, magnesium oxide, anhydrous citric acid; sodium phosphate tablets; oral sulfate solution/tablets; magnesium citrate; bisacodyl; and off label lactulose.