BÜHLMANN Polyethylene glycol (PEG) Allergens

BÜHLMANN is proud to release the first Polyethylene glycol (PEG) Allergens for the Flow CAST® basophil activation assay. During the last weeks, we received many requests from experts in the field who asked for PEG allergens, The Flow CAST® is a powerful laboratory test to investigate the patients’ hypersensitivity reactions to PEG. These reactions are suspected to be responsible for the rarely observed adverse reactions to the COVID-19 vaccines.

Allergic and adverse reactions to vaccines are rare and the occurrence of such events should not deter patients from getting a vaccination. Maintenance of vaccine safety requires a proactive approach to maintain public confidence1.

Vigilance and clinical management of patients during vaccinations are essential, but this approach should also include the understanding of any allergic or adverse reactions’ mechanisms of action, identification of the culprit substance in the vaccines’ formulation, and a proposed warning for people at risk, before getting the vaccine.

Polyethylene glycols (PEG) are ingredients in the lipid formulation in some of the COVID-19 vaccines and are suspected to be the cause in adverse reactions1,2. First international recommendations clearly advice that patients with hypersensitivity reactions to PEG and Polysorbate should not be vaccinated.

Flow CAST® basophil activation testing is a powerful laboratory testing opportunity to investigate a potential patient’s hypersensitivity reaction to PEG3,4.

Basophil Activation Test (BAT)

The Basophil Activation Test (BAT) resembles an allergic reaction in a vial. The test is based on a drawing a simple venous blood sample from an individual. The Basophils are the allergic cells present in such a sample. By adding the suspected allergenic substance, like PEG, to a small amount of blood in a test tube, basophils can be specifically activated. This BAT is a reliable biomarker for potential in vivo hypersensitivity reactions to the tested substance. The basophil activation results in the degranulation and release of pro-inflammatory mediators as well as the expression of activation markers. The BAT test detects the expression of such markers like CD63 by a flow cytometry technique.

The knowledge of PEG hypersensitivity reactions is limited as compared to other drugs. PEG has for long been considered safe and used in several drugs, cosmetic, food preparation & medical devices.  Its role as a hidden allergen has been only recently discovered. So far the typical diagnostic investigation relies on skin prick test with a series of PEG at different molecular weights5.

BAT assays, such as Flow CAST® are safe and non-invasive alternatives to allergic tests in-vivo and validated support to investigate PEG hypersensitivity reactions in the context of adverse reactions to COVID-19 vaccines.

Adverse reactions to the first COVID-19 vaccine were documented in late December 20206, which were the catalyst for BÜHLMANN to investigate diagnostics for said hypersensitivity reactions.

For that reason, we are diligently working in the development and release of a package of CAST® allergens for our Flow CAST®. Since it is known that PEGs at different molecular weights may result in different reactivity of patients’ basophils, we are working on more than one PEG to maximize the chance to highlight a patient response.

Today we are proud to release the first PEG allergen:

  • PEG 2000 (order code, BAG2-CPEG2)
  • DMG PEG 2000, 1,2-Dimyristoyl-rac-glycero-3-methoxypolyethylene glycol-2000 (order code, BAG2-CPEG3)

To immediately respond to the many requests from the specialists in the field, the product is available in a RUO version. Additional PEG allergens will follow.


  1. Castells, M. C. & Phillips, E. J. Maintaining Safety with SARS-CoV-2 Vaccines. N. Engl. J. Med. 1–7 (2020) doi:10.1056/nejmra2035343.
  2. Cabanillas, B., Akdis, C. & Novak, N. Allergic reactions to the first COVID‐19 vaccine: a potential role of Polyethylene glycol? Allergy 0–1 (2020) doi:10.1111/all.14711.
  3. Wenande, E. & Garvey, L. H. Immediate-type hypersensitivity to polyethylene glycols: a review. Clin. Exp. Allergy 46, 907–922 (2016).
  4. Cerdá, V. J., Pacheco, R. R., Witek, J. D., De La Calle, F. M. M. & De La Sen Fernández, M. L. Immediate hypersensitivity to polyethylene glycols in unrelated products: When standardization in the nomenclature of the components of drugs, cosmetics, and food becomes necessary. Allergy, Asthma Clin. Immunol. 15, 1–5 (2019).
  5. Stone, C. A. et al. Immediate Hypersensitivity to Polyethylene Glycols and Polysorbates: More Common Than We Have Recognized. J. Allergy Clin. Immunol. Pract. 7, 1533-1540.e8 (2019).
  6. Garvey, L. H. & Nasser, S. Anaphylaxis to the first COVID-19 vaccine: is polyethylene glycol (PEG) the culprit?Br. J. Anaesth. 8–10 (2021) doi:10.1016/j.bja.2020.12.020.