D3.71 - Anaphylaxis Induced by Macrogol: A Case Report

Introduction:  

Polyethylene glycol (PEG) has regained relevance after being implicated as a potential allergen in COVID-19 vaccines. PEG is a synthetic polymer widely used in pharmaceutical, food, and cosmetic formulations. Its molecular weight ranges from 200 to 35,000 Da, with higher molecular weights capable of acting as haptens or even eliciting allergic reactions independently.  

Case Report:  

A 52-year-old male with dyslipidemia and no prior history of atopy reported experiencing an allergic reaction one year ago after ingesting Plienvue® (Macrogol 3350, sodium ascorbate, anhydrous sodium sulfate, ascorbic acid, sodium chloride, and potassium chloride) as a bowel preparation for colonoscopy. Immediately after the first dose, he developed sneezing, rhinorrhea, urticarial lesions on the lower limbs, and dyspnea. He presented to the emergency department, where he was treated with dexchlorpheniramine and methylprednisolone, leading to complete resolution of symptoms within two hours.  

Results:  

A skin prick test with Plienvue® and macrogol was performed, yielding negative results. A subsequent oral provocation test with 3.5 g of macrogol induced urticarial lesions on the upper limbs and pharyngeal pruritus within 20 minutes, which resolved after administration of epinephrine, methylprednisolone, and dexchlorpheniramine.  

Discussion:

PEG is a ubiquitous compound found in numerous substances, and its allergenic potential has been described through various mechanisms. Its molecular weight has been suggested as a contributing factor to hypersensitivity reactions. Notably, macrogol with molecular weights of 3,350 and 4,000 Da has been most frequently associated with hypersensitivity reactions, as observed in our patient.