Polyethylene Glycol: Not Just a Harmless Excipient

Cutaneous adverse effects of the available COVID-19 vaccines

“…Low molecular weight (LMW) (200–700kDa) PEGs are liquids, while high molecular weight (HMW) (1000–7500kDa) PEGs are solids. Usually, HMW allergens produce type I hypersensitivity, while contact sensitization is mainly reported with low molecular weight PEGs, for example, PEG 200 to PEG 400 ( 19 ).…”

Adverse reactions to COVID‐19 vaccines: A practical approach

“…Only small case series of PEG allergic patents have been reported despite the widespread presence of these compounds in common toiletries, household chemical agents and drugs. [8][9][10] The seminal paper by Wenande reported 37 patients with PEG hypersensitivity and brought this rare allergy to the attention of a wider audience. 8 No large epidemiological studies have been carried out to ascertain the precise incidence of PEG allergy in the general population.…”

“…All tests should be performed by an allergist/immunologist experienced in the diagnosis of PEG allergy. Standardized ST protocols and in vitro tests are a work in progress and individual patients may need tailored testing regimes, 9,10 • Skin testing should be tailored to the suspected mechanism of the reaction, for example SPT and IDT with immediate reading for immediate reactions and IDT with late reading and patch test for Currently, the only pure clinical grade of PEG routinely available for testing is 10% Macrogol solution (PEG 3350) in the form of commonly used laxatives. 9,10,12,14 • Drug provocation test (DPT) with the relevant PEG-containing drug might be considered in case of a discrepancy between history and skin tests but only if ST are completely negative.…”

“…Case reports of PEG anaphylaxis first appeared in the early 1990s. Only small case series of PEG allergic patents have been reported despite the widespread presence of these compounds in common toiletries, household chemical agents and drugs 8‐10 . The seminal paper by Wenande reported 37 patients with PEG hypersensitivity and brought this rare allergy to the attention of a wider audience 8 .…”

“…The LMW PEG can cause delayed hypersensitivity reactions: contact dermatitis/rash on repeated exposure. It is not clear whether repeated cutaneous/mucosal exposure contributes to IgE sensitization and predisposes to severe allergic reactions in response to HMW PEGs [8][9][10]. Gastrointestinal absorption of PEG above MW 1000 g/mol is poor and a large amount (grams) must be ingested (eg macrogol laxative [PEG3350]) to trigger a reaction.…”