Polyethylene Glycol-Induced Systemic Allergic Reactions (Anaphylaxis)

Area of Science:

• Clinical Immunology
• Allergy and Immunology
• Drug Hypersensitivity

Background:

• Polyethylene glycols (PEGs), also known as macrogols, are widely used hydrophilic polymers in various consumer products and medications.
• Suspected PEG allergy presents diagnostic challenges, often leading to misdiagnosis and complex clinical management.
• Anaphylaxis and severe allergic reactions are potential consequences of PEG exposure.

Purpose of the Study:

• To report the largest case series to date of confirmed polyethylene glycol (PEG) allergy.
• To describe the clinical presentation and diagnostic findings in patients with PEG allergy.
• To propose a safe investigation algorithm for suspected PEG allergy.

Main Methods:

• Retrospective analysis of 5 cases with confirmed PEG allergy.
• Skin testing (prick and intradermal) with index medications and PEGs of varying molecular weights.
• Oral challenges were performed in one case.
• Review of clinical management and diagnostic outcomes.

Main Results:

• Four out of five patients experienced anaphylaxis to PEG-containing medications, with one case of near-fatal cardiac arrest.
• Skin testing confirmed PEG allergy in three patients via skin prick tests and one via intradermal testing.
• Two patients developed anaphylaxis post-intradermal PEG testing; one experienced a systemic allergic reaction post-skin prick testing.
• All patients were initially misdiagnosed with allergies to multiple medications, complicating their care.

Conclusions:

• Accurate diagnosis of PEG allergy is critical to avoid misattribution of allergies to other medications.
• Investigating suspected PEG allergy requires specialized knowledge, careful planning, and appropriate dilutions to mitigate risks.
• A proposed algorithm and guidance on PEG molecular weights and skin test dilutions are essential for safe investigation in specialist drug allergy centers.