D3.265 - Biphasic anaphylaxis secondary to polyethylene glycol in a pediatric patient: a case report

Background

Polyethylene glycol (also known as Macrogol, PEG, or E1521) is a widely used excipient in drugs, cosmetics, hygiene products, and processed foods. It is not a protein, but a polymer of ethylene oxide. While it is a rare cause of allergy, its presence in certain vaccines against SARS-CoV-2 has made it more well-known in recent years. Despite being an uncommon allergen, polyethylene glycol can trigger severe reactions. It is mainly found in laxative solutions, tablets, and corticosteroids.

Case Report

We report the case of a four-year-old child referred to our outpatient clinic for a suspected drug allergy after having been treated with polyethylene glycol 4000 for constipation. The patient had no known previous medical conditions and was regularly treated with an oral solution of polyethylene glycol 4000 when constipated.

In June 2024, the patient was given a dose of the oral solution of polyethylene glycol 4000 due to constipation and immediately presented with mild urticaria and eyelid edema, with no other symptoms. The patient was taken to the Emergency Room (ER) by his mother and was later referred to our outpatient clinic. The patient was taken to the emergency room to treat the reaction and was later referred to our department for further evaluation.

As part of the allergy study, we conducted a skin-prick test with the oral solution of polyethylene glycol 4000, which was negative. We then proceeded with an oral drug challenge test, which was positive 30 minutes after the first dose (2g). The patient developed pruritus on the skin and eyes, followed by generalized urticaria, erythema, and sneezing. He was treated with intramuscular epinephrine (200 mcg), oral dexchlorpheniramine (1 mg), and oral prednisolone (21 mg), and was kept under observation. One hour later, the patient’s symptoms recurred, with intense palmar pruritus and sneezing, so we administered a second dose of intramuscular epinephrine (200 mcg) and oral dexchlorpheniramine (1 mg). He then developed no further symptoms.

The patient was diagnosed with biphasic anaphylaxis secondary to the administration of polyethylene glycol 4000 and was advised to avoid this drug, as well as any other products that may contain it as an excipient or additive (including other drugs, vaccines, foods, cosmetics, and hygiene products).

Conclusion

To our knowledge, this is the first case described in the medical literature of biphasic anaphylaxis in a pediatric patient secondary to polyethylene glycol 4000, which is widely used as a laxative for constipation and prior to colonoscopy procedures. It is also present as an excipient or additive in other drugs, foods, and hygiene products. Physicians should be aware of this potential allergy and consider it when patients report allergic reactions to a variety of products.